Preface

Professor Maki Kawai

Chair, MSF Steering Committee
Director General, Institute for Molecular Science
Professor Emeritus of the University of Tokyo

Cultivating new horizons for Condensed Matter Science
The Millennium Science Forum (MSF) was established based on the voices of seniorscientists who lead the modern research with the intention of cultivating new horizons forCondensed Matter Science.
On this occasion of 20 years of the MSF, we would like to show the how the mission of the
MSF was conceived and what was attained by twenty-two talented prize winners. The start
was in 1998, when Professors Noboru Miura, Hidetoshi Fukuyama, the late Koichi Kitazawa
and Sir Peter Williams met in Tokyo and came up with the idea of the MSF which wasstarted in the following year, 1999. The Sir Martin Wood Prize was set as the core programof the MSF and Mr. Yasunobu Nakamura of NTT, currently Professor of the University ofTokyo, became the 1st awardee. In November 2018, the twentieth Sir Martin Wood Prize
will be awarded to Associate Professor Yoshihiko Okamoto of Nagoya University.
Here we showcase twenty-two Prize Winners with their achievements and theirdevelopment since the MSF was founded. Successful advancement in their personal careers
indicates the promotion of Condensed Matter Science and individual descriptions of theirresearch represents the development of Condensed Matter Science itself in two decades. We
are confident that you will enjoy the new era of the field. Sir Martin Wood Prize winners are
given the opportunity of lecture trips to UK universities and institutes in Germany. This is anoteworthy experience that ties together young generations of Japan and the UK.
The MSF has been always been kindly supported by the British Embassy in Tokyo, andalso by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of
Japan. We are grateful to Mr. Paul Madden, British Ambassador to Japan, and to Mr. Touichi
Sakata, former vice minister of MEXT, for their contribution of warm words to this book.
Last but not least, twenty years of the MSF would not be possible without the devotion of
Oxford Instrument KK. Without the encouragement by Mr. Jiro Kitaura, former president,
the MSF would not have existed. The steering committee of the MSF is grateful for Oxford
Instruments’ continued support over the past twenty years and for the future.

20 years of the Millennium Science Forum3

Contents
Page

Preface3Founder’s Message

6

Professor Maki Kawai (Chair, Millennium Science Forum Steering Committee)

Professor Noboru Miura (Founder, Millennium Science Forum)

Greetings

Sir Martin Wood (Founder, Oxford Instruments)
Sir Peter Williams (Member of Millennium Science Forum Steering Committee

8
10Professor Robin Nicholas (University of Oxford)
Mr. Paul Madden (British Ambassador to Japan)
Mr. Touichi Sakata (Former vice minister, MEXT)

12
14
16

			

Former Chairman, Oxford Instruments)

Introduction to the Sir Martin Wood Prize

Professor Hidetoshi Fukuyama (Chair, Sir Martin Wood Prize Selection Committee)

18

Locations of Sir Martin Wood Prize Lectures

19

Lecture Trip Memories

20

Brief History of the MSF

22

Messages from the Sir Martin Wood Prize Winners

25

Tony Ford (MSF Secretariat)

70

List of the Winners in alphabetical order

Appendix72

Prize Ceremony Memories
Record of the MSF
Steering Committee and Selection Committee members

76

Guest Speakers at the Millennium Science Forum77

20 years of the Millennium Science Forum

5

Founder’s Message

Professor Noboru Miura
Founder, Millennium Science Forum

Professor Emeritus of the University of Tokyo“How can we contribute to building a bridge between the science communities of Japanand the UK by promoting the activities of top young researchers, rather than simply doing
business in Japan?”“Can we search for a scheme together?”
In 1997 Mr. Kitaura of Oxford Instruments asked me these unexpected, and at the sametime, difficult questions so I consulted with Professor Koichi Kitazawa and Professor
Hidetoshi Fukuyama.
I was familiar with various cases of joint programmes between academia and industry thatin many cases had glorious start-ups, but unfortunately did not last.
I noticed a variety of reasons for such programmes being unsustainable so I was mindful that
we needed to discuss in detail to reach a common understanding. Our concerns disappeared
when we talked further with Mr. Kitaura and he assured us that Oxford Instruments direction
will be different to the “unsuccessful examples” we had seen in the past and he told us:“We just want to bridge the science communities of Japan and the UK by encouraging young
scientists without linkage to the Oxford Instruments business, hence the scheme will not havethe company name associated with it”
This was the first time we had heard of a programme that did not have the name of thesponsor or some specific promotional target combined with it, so we immediately decided
to support the activity and quickly moved ahead to create the whole scheme. At this stage I
received strong encouragement from the Oxford Instruments Chairman, Sir Peter Williams, tolead the initiative with Oxford Instruments Japan.
The next difficult question we faced was naming and identifying the mission and spirit of6

20 years of the Millennium Science Forum20 years of
the Millennium Science Forumthe activity. After some discussions we decided to call it the “Millennium Science Forum”(MSF) with a vision of “Looking to the Future” with commitment, consistency and continuity.
At the same time we decided that the MSF should have a core program to give awards toyoung researchers. I was happy that Sir Martin Wood, Founder of Oxford Instruments, kindly
agreed to call the award the “Sir Martin Wood Prize” and we asked our academic colleagues
to support and become involved with the prize. Based on these fundamental points, everything
has run smoothly since then.
In 1999, we were greatly honored that HRH The Princess Royal and many distinguishedguests attended the inaugural event at The British Embassy in Tokyo.
The MSF has now been recognized by the scientific communities in both Japan and the UK.
Below is the charter adopted for the MSF upon which our entire activities are based on andgives us strong encouragement to continue.
1. Oxford Instruments name is not directly associated with the MSF however following thewill of the founder of the company, and to motivate people externally and internally, thename of the award is the “Sir Martin Wood Prize”
2. From the outset the emphasis will be on excellent results to maintain the activities,
including management structure of the MSF.
3. Through these activities, our objective is to build bridges between the scientificcommunities of Japan and the UK.
I strongly hope that by keeping our original concept the MSF will continue to prosper
through the constant adoption of innovative ideas and design.

20 years of the Millennium Science Forum

7

Greetings

Sir Martin Wood
Founder, Oxford Instruments

It was in 1955 that I first started working with physicists carrying out research in
aspects of Condensed Matter Physics – then known as Solid State Physics. I was working
under Dr. Nicholas Kurti at the University of Oxford's Clarendon laboratory, managing
the High Magnetic Field facility, and developing new types of resistive magnet andresearch equipment for their experiments.
Other universities wanted similar equipment so, in 1959, with the help of my wife,
Audrey, I started the Oxford Instruments Company. This was two years before theAmerican breakthrough in superconductivity which resulted in useable superconductors
for magnets. It led to a great expansion of research in the field, and rapid growth at
Oxford Instruments.
Condensed Matter Physics has come a long way since then. I am full of admiration for
the research work and achievements of the scientists who have won this Prize, which
they have outlined in this booklet. I am very happy to have met many of the prizewinners in Tokyo, and most of them in my house in Oxfordshire.

8

20 years of the Millennium Science ForumI would like to thank the eminent scientists in the Millennium Science Forum who havegiven their time to reading all the submitted papers and judging between them. Especial
thanks must go to Professor Noboru Miura, who I have known for many years and who
was the first chairman of this committee. He has worked tirelessly and has accompanied
most of the prize-winners on their lecture tours in the UK. Many thanks also to Tony
Ford, who first developed this project with Professor Miura, and has organised thepresentations and the lecture tours from the beginning.
I hope the prize will continue to encourage and reward young scientists in this field formany years to come.

20 years of the Millennium Science Forum9Sir Peter Williams

Member of Millennium Science Forum Steering Committee
Former Chairman, Oxford Instruments

During 1998, a small group of British and Japanese scientists and technologists
gathered in the City Club of Tokyo, in Akasaka, to discuss how to mark the forthcoming
millennium celebrations. Convened by Jiro Kitaura, then-president of Oxford Instruments
KK, the group hatched a plan under his leadership to hold an annual seminar, if possibleat the British Embassy, Tokyo, to showcase cutting edge developments in Japan incondensed matter physics. The Millennium Science Forum was born.
Those present—Professor Noboru Miura, Professor Hidetoshi Fukuyama, the lateProfessor Koichi Kitazawa and I—further proposed to mark the occasion each year withthe award of a prize to a young Japanese scientist, who would subsequently visit the UK
to give prestige lectures at the University of Oxford and other leading universities. This
plan has since been extended to include German research institutions.
By chance, in March 1999, the planned announcement of the MSF at the British
Embassy, Tokyo coincided with a visit to Japan by Her Royal Highness Princess Anne,
the Princess Royal, to attend a meeting of the International Olympic Committee, of which
she is a member. She enthusiastically agreed to join me and Sir David Wright GCMG
LVO, then HM Ambassador, at the ceremony. Thus, the MSF enjoyed a royal opening.

10

20 years of the Millennium Science ForumThe Princess Royal’s good wishes at the launch of the MSF have undoubtedly borne
fruit. The alumni list of winners of the Sir Martin Wood Prize comprises emerging
leaders in their fields in Japan, with increasingly global reputations. The 20th such prize
will be awarded in 2018.
The UK and Japan have always enjoyed close partnerships in science, and theexchange of visits and ideas between young scientists in our two nations both strengthensand deepens this bond. In years to come, as the prize winners rise in prominence in theirrespective fields, the enhancement in mutual understanding between the scientific leadersof the UK and Japan will have a significance and importance well beyond the sphereof science. Today, in a world filled with uncertainties, these relationships constitute a
precious asset.
On behalf of all my colleagues in the MSF, may I in conclusion thank HM Ambassador
Paul Madden CMG for his continuing support; we are indebted to him and his
predecessors over the past 20 years for their invaluable and positive contribution.

20 years of the Millennium Science Forum

11

Professor Robin Nicholas

Member of Millennium Science Forum Steering Committee
University of Oxford

It is a great pleasure to contribute to this celebration of 20 years of the Millennium
Science Forum and the Sir Martin Wood Prize. As with many important institutions theorigins of the foundation lie in the close personal interactions developed by individuals,
in particular Professor Noboru Miura and Sir Martin Wood. Noboru first came to the
UK as a relatively young visitor in his early thirties to work in the University of Oxford
in the research group of Professor Tony Stradling on the properties of semiconductors inhigh magnetic fields, in the laboratory first set up by Sir Martin together with Professor
Nicholas Kurti. This proved to be a formative experience leading to a lifelong seriesof collaborations and interactions with UK scientists. About ten years later a young
Japanese graduate student studying at the University of Oxford walked into the gardenof Sir Martin Wood, which he had opened to the public for a few days. Sir Martin’s
garden is on the banks of the Thames, which the student was studying as a historicallyimportant transport route. The student told Sir Martin that he lived in the ‘middle’ ofTokyo and they struck up an immediate friendship. Within a few years the student had
become Crown Prince Naruhito and the two have remained good friends ever since. Both
Noboru and Sir Martin were convinced of the great benefits of intellectual and cultural
exchange at an early career stage, so they persuaded Oxford Instruments to help fundthe Millennium Science Forum to promote this exchange and to give it a clear scientificfocus in the area of condensed matter physics which had been vital to both of them andto the business of Oxford Instruments in both the UK and Japan.

12

20 years of the Millennium Science ForumTo achieve this they set up the prize with: The winner to be a person under 40, having
performed research in a Japanese institute, selected by a committee of distinguishedJapanese scientists headed for many years by Professor Noboru Miura, Institute of Solid
State Physics, Tokyo and now by Professor Hidetoshi Fukuyama, Tokyo University of
Science. The prize awarded being ¥500,000 and the opportunity to lecture at UK & EU
Universities.
The prize has been instrumental in promoting the careers of many of the prize-winners
through its special formulation of a lecture tour to prestigious Universities mainly in
the UK, combined with a prize winning presentation in the UK embassy in Tokyo withspecial guest lecturers and an audience of many of the top scientists in Japan, hosted by
the British Ambassador. Speaking personally, having attended the lectures from all of the
prize winners, presented in the Sir Martin Wood lecture theatre in Oxford, I never cease to
be impressed by the imagination, skill and academic excellence of the science which they
have done in Japan. The elements of cultural exchange have not been forgotten either. As
Professor Yasunobu Nakamura, the first prize winner, says in his message his visit wasalso the first time that he was introduced to another British phenomenon, Harry Potter!
On a final note I would also like to give special thanks to Tony Ford, who has been
unstinting in his efforts to ensure the smooth running of the prize and to ensure that boththe prize winners and the UK institutions have benefited enormously from their lecture
tours.

20 years of the Millennium Science Forum

13

Mr. Paul Madden
British Ambassador to JapanI am delighted to congratulate the Millennium Science Forum on the 20th anniversaryof the Sir Martin Wood Prize. The Prize has been very successful in motivating young
researchers in their quest to further the understanding of the fundamental properties ofmaterials and matter.
Japan and the UK are strongly committed to science and innovation. Both countries
have a long history of making significant contributions to scientific understanding andimproving the lives of people around the world. Collaborations between scientists areof vital importance in the extensive relationship between the two countries. The Sir
Martin Wood Prize allows international relationships to be formed in the early stage of ascientist’s careers. I am sure that the experience of the winners visiting UK Universities
and research institutes provides them with inspiration for new ideas for their research.
The prize selection committee has an excellent record of choosing recipients of
the Sir Martin Wood Prize who have performed world class research. Leading UK
scientists recognize the value of the prize and are always keen to host the Sir Martin
Wood Lectures. I am also grateful to Oxford Instruments and Sir Martin Wood forestablishing and sustaining the Millennium Science Forum and Sir Martin Wood Prize

14

20 years of the Millennium Science Forumfor so many years. It is important that both Japan and the UK continue to cultivate longterm partnerships between the academic and industrial research communities in our two
countries.
In addition to the scientific discussions the prize winners have in the UK, they are alsoable to gain insights and understanding of the culture and heritage of the UK that will
benefit their future collaborations and relationships with their counterparts. I hope that
the Sir Martin Wood Prize will continue to motivate young Japanese scientists to initiateinnovative research and collaborate with UK researchers.
I wish the Sir Martin Wood Prize every success for the future.

20 years of the Millennium Science Forum

15

Mr. Touichi Sakata

President of the Japan Space Forum
Former Vice Minister of the Ministry of Education,
Culture, Sports, Science and Technology

Congratulations on the 20th anniversary of the establishment of the Millennium
Science Forum!
The Millennium Science Forum (MSF), which was established to foster the exchangeof science and technology between Japan and the UK, was founded in March 1999. In
2018 it will award the 20th Sir Martin Wood Prize.
Given that I have participated in the Japanese government for the promotion ofscientific research, I sincerely congratulate the MSF on its 20th anniversary.
I would like to express my deep gratitude and respect to British physicist Sir Peter
Williams and Professor Emeritus Noboru Miura of the University of Tokyo who
dedicated themselves to founding the MSF. My sincere thanks, too, to all the otherindividuals in Japan and the UK who have been involved in the foundation and operationof the MSF.
In Japan at present, contributing to the realisation of innovation using outcomes fromscientific research is considered crucial. Research on advanced materials science basedon physics and chemistry is one of the important fields of research that will pave the way
to innovation, including the development of revolutionary devices. The MSF’s decision
to promote condensed matter science is one response to these developments.

16

20 years of the Millennium Science ForumI applaud the establishment of the Sir Martin Wood Prize that is awarded by the MSF
each year, to a young condensed matter scientist working in Japan.
I participated in the MSF on 4 occasions, each time I attended the Sir Martin Wood
Prize ceremony, which is held annually in the British Embassy, Tokyo, I noticed a wide
range of researchers from both Japan and the UK. I also noticed that the MSF contributes
greatly to promoting intimate science and technology exchanges between both countries.
Both Japan and the UK are island countries, but they promote science and technology
to, and support exchanges with, other parts of the world. As we share such goals, wehave been able to deepen our bilateral science and technology exchanges through the
MSF over the past 20 years. These exchanges have undoubtedly contributed to thedevelopment and strengthening of friendship between our two countries.
I believe that the MSF will continue to offer exchange opportunities to researchers
based in Japan and the UK beyond its 20th anniversary. I also hope that past and future
recipients of the Sir Martin Wood Prize will play active roles in the development ofscience worldwide.

20 years of the Millennium Science Forum

17

Introduction to the Sir Martin Wood Prize

Professor Hidetoshi Fukuyama

Chair, Sir Martin Wood Prize Selection Committee
Adviser to the Chair and the President, Tokyo University of Science
Professor Emeritus, the University of Tokyo

The Sir Martin Wood Prize was established in the first committee meeting of theMillennium Science Forum (MSF), on 23rd January 1999 at Oxford Instruments KK, after
preliminary discussions on 23rd July 1998 and 11th October 1998.
Jiro Kitaura, then-president of Oxford Instruments KK, had expressed with vigour hisstrong vision for progress in science and technology. He described the mission of the MSF
as follows:• To promote science in the 21st century by increasing the opportunity of discussion
among scientists• To promote scientific exchange between the UK and Japan• To award prizes to young scientists
This mission of the MSF remains unchanged. Its award for young scientists was
naturally named the Sir Martin Wood Prize, which was suggested by Professor Koichi
Kitazawa in the second preliminary meeting. To be eligible for the prize, applicants must:• Specialise in condensed matter science• Perform their research in a Japanese university or institute• Be under 40 years of age in the year of their application; any nationality may apply
Besides a financial award of ¥500,000, the Sir Martin Wood Prize has a unique feature:
the recipient has the opportunity to lecture at universities in the UK and European Union,
which stimulates and helps every recipient to step up onto the international stage.
This special arrangement reflects the nature of the sponsor, Oxford Instruments KK,
bridging Japan and UK-EU, and the vision thereof.
The Millennium Science Forum was first held on 9th March 1999, in the New Hall of
the British Embassy, Tokyo as a ceremonial activity. HRH The Princess Royal delivered
greetings and gave an Honorary award to Professor Hiroshi Yasuoka, former director of theInstitute of Solid State Physics, the University of Tokyo. Following the presentation of theaward Professor Noboru Miura described the Millennium Science Forum’s mission and an
introduction letter from Sir Martin Wood was read by Oxford Instruments’ Jiro Kitaura.

18

20 years of the Millennium Science ForumThe first Sir Martin Wood Prize was awarded to Yasunobu Nakamura on 17th November
1999, in the same place.
The status of any prize depends on the committee that chooses its winners. The membersof the Sir Martin Wood Prize’s selection committee to date are listed in the appendix.
Quite often another board, for example an honorary board, sits above the selection
committee, but that is not the case for the Sir Martin Wood Prize, reflecting the strong
wish of Oxford Instruments, which is again very rare.
Because of the high-level scientific activities of each member of the selection committee,
every selection meeting has been a very lively occasion for experts to exchange opinions
frankly. It is an occasion for the committee to appeal or learn new developments incondensed matter science.
To date, the Sir Martin Wood Prize has been awarded to 22 recipients, who in total gave
82 lectures as shown in the Figure below, not only in the UK but also in Germany—aninitiative that started in 2015.
In 2007, the steering committee was created from the selection committee, for theeffective management of the Millennium Science Forum aside from the selection of the Sir
Martin Wood Prize recipient.

Locations of Sir Martin Wood Prize Lectures
Sir Martin Wood Prize lectures 2000 to 2018 (82 in total)

Glasgow (1)Lancaster (1)Max Planck Institute, Stuttgart (4)Manchester (6)Leeds (2)Daresbury (1)York (5)Liverpool (1)Sheffield (2)Warwick (2)Nottingham (4)Oxford (19)Cambridge (14)Bristol (2)Royal Holloway (1)Cardiff (1)UCL (10)Southampton (2)Royal Society (1)Exeter (1)Imperial College (1)Surrey (1)20 years of the Millennium Science Forum

19

Lecture Trip Memories

20

Professor Shirahama at Royal Holloway with Professor Miura and Professor Michael Lea (2002)

Professor Kimura at Sir Martin’s home with Mrs.
Miura (2006)

Professor Ohtomo in Cambridge with Professor
Fukuyama (2008)

Professor Saitoh and Professor Ono visit Sir Martin & Audrey Wood's home (2009)

Professor Hayashi visiting Sir Martin (2015)

Professor Kim visiting Liverpool University(2010)

Professor Satoh with Professor Takagi at the Max
Planck Institute (2016)

Sir Martin showing Professor Shibata where Oxford Instruments started (2014)

20 years of the Millennium Science ForumProfessor Suenaga with his wife and Professor
Kawai in Cambridge (2007)

Professor Ohtomo in Oxford with Professors Miura,
Fukuyama, Briggs and Mr. Matsuura Science Attaché from the Japanese Embassy in London (2008)

Dr. Kim at Sir Martin’s home (2010)

Professor Murakami with Professor Eaves in Nottingham (2011)

Professor Chiba visiting Newton’s birthplace withProfessor Miura (2013)

Professor Ishizaki with Sir Martin and Audrey
Wood (2017)

Professor Robin Nicholas welcoming Professor
Yamamoto to Oxford (2018)

Professor Yamamoto meeting Sir Martin and
Audrey Wood (2018)20 years of the Millennium Science Forum

21

Brief History of the MSF

Tony Ford
MSF Secretariat

Professor Noboru Miura and Sir Martin Wood are the two prominent figures instrumental in the success of the Millennium Science Forum.
Sir Martin had just retired as deputy chairman of Oxford Instruments after 41 years’ service when the MSF started in 1999, he readily agreed for the prize to be in his name andwelcomed the opportunity to remain involved with the company in a role where he could
meet customers and follow technological trends.
Professor Noboru Miura was a post-doctoral researcher in the University of Oxford in1972 when he first met Sir Martin and was happy to rekindle his friendship through the
MSF which matched their mutual enthusiasm to motivate researchers to expand international collaborations. Professor Miura’s contribution in increasing UK Japan scientific exchange was recognized by the UK Government and in 2006 he was awarded an OBE (Orderof the British Empire). Similarly Sir Martin was awarded The Order of the Rising Sun,
Gold Rays with Neck Ribbon by the Japanese government in 2008.
The opportunity for the Sir Martin Wood Prize winners to visit the UK and meet theircounterparts with expertise and research interests in the same area of physics, allows thewinners to have detailed technical discussions as well as exchanging views on researchfunding, equipment specifications and in several cases, start new collaborations or augment existing arrangements.
We arrange for the prize winners to visit one of Oxford Instruments’ facilities and show
them firsthand how equipment is designed and manufactured. When appropriate we also
discuss specific requirements and features for new equipment. Almost all the winners havevisited Sir Martin and Audrey Wood at their home in Little Wittenham where they arealways given a warm welcome. Sir Martin takes great pride in walking round his garden
with the winners and talking about the history of Oxford Instruments by showing some ofthe devices made by the company in the early days.

22

20 years of the Millennium Science ForumThe lectures are normally in the early summer at 4 or 5 venues arranged between Monday and Friday. In addition to the academic programme, when time permits we arrange
visits to places that have historical or cultural importance to foster greater understandingof the UK. Prize winners have visited Isaac Newton’s birthplace, Green’s windmill; homeof theoretician George Green, they have seen James Clerk Maxwell’s original desk andEinstein’s script preserved on a blackboard he used for a lecture. In some cases winners
are able to return to the UK and spend more time with their counterparts in Universities
they visited on the lecture tour or even visit for a vacation and have a more leisurely time.
The MSF is now endorsed by 17 academic societies and organizations. We have beenvery fortunate to have strong support from the British Embassy in Tokyo from the startand from 2007 the Japanese Embassy in the UK has endorsed the Sir Martin Wood Prize
lectures with an initiative started by the then Science Attaché, Mr. Shigekazu Matsuura.
Since then a senior representative from the Japanese Embassy in London joins one of the
UK lectures and makes a brief address to the audience on the importance of Japan UK scientific collaborations.
From 2015, thanks to the generous support of Professor Hidenori Takagi, we have beenable to extend the lecture tour to include the Max Planck Institute in Stuttgart.
It is always very pleasing to see prize winners from previous years attending the prize
ceremony at the Millennium Science Forum to welcome the new winner to their alumni
and give advice on how to structure their lectures for UK audiences.
On a personal note, it is a tremendous pleasure to accompany the prize winners on theirlecture visits and inspiring to hear their passion to make discoveries and increase their understanding in their area of expertise. Chatting with the winners informally on a wide rangeof subjects is always enjoyable and makes me realize that in addition to the winners excelling academically, they are all very warm hearted individuals who always bring out the bestin those around them. Additionally all the committee members have devoted large amountsof their personal time to MSF activities that have contributed to the success over the past
two decades. As a result of the distinguished personal standing of the committee members
and prize winners, the MSF has strengthened UK Japan collaboration in scientific researchand research based industry and is a successful illustration of “Science Diplomacy”.
I would like to pay tribute to the many other people, including colleagues in Oxford
Instruments, who have contributed to the success of the MSF since its inception. In particular we should express gratitude to the Chief Executive of the company who has theforesight to recognize the importance of having strong connections with leading edge researchers in Japan. Hidemi Kurosawa deserves a special mention for her enthusiasm andmeticulous planning that ensures the prize selection process and MSF events always proceed smoothly.

20 years of the Millennium Science Forum

23

24

20 years of the Millennium Science ForumMessages from the Sir Martin Wood Prize Winners
Page

1st 1999

26

Tokushi Kizuka

Joint 2nd 2000

28

Katsuya Shimizu

Joint 2nd 2000

30

Keiya Shirahama		

3rd 2001

32

Ichiro Terasaki		

4th 2002

34

Toshimasa Fujisawa		

5th 2003

36

Yuzo Ohno			6th 2004

38

Tsuyoshi Kimura		

7th 2005

40

Kazutomo Suenaga		

8th 2006

42

Akira Ohtomo		

9th 2007

44

Teruo Ono

Joint 10th 2008

46

Eiji Saitoh

Joint 10th 2008

48

Yousoo Kim			

11th 200950

Shuichi Murakami		

12th 201052

Yukio Kawano		

13th 201154

Daichi Chiba			

14th 201256

Naoya Shibata		

15th 2013

58

Masamitsu Hayashi		16th 2014

60

Takuya Satoh			

17th 2015

62

Akihito Ishizaki		

18th 2016

64

Michihisa Yamamoto

19th 201766

Yoshihiko Okamoto		

20th 2018

68

Yasunobu Nakamura

20 years of the Millennium Science Forum

25

Winner in 1999

Yasunobu Nakamura

Current title and affiliation
Professor, Research Center for Advanced Scienceand Technology, The University of Tokyo, Team
Leader, Center for Emergent Matter Science, RIKEN

1990: B.S., Department of Applied Physics, The University of Tokyo
1992: M.S., Superconductivity Research Course, The University of Tokyo
1992-2011: Researcher, Senior Researcher, Principal Researcher, Research Fellow, NEC Corporation
2001: Visiting Researcher, Department of Applied Physics, Delft University of Technology (Netherlands)
2002-2013: Researcher, RIKEN
2011: D. Eng., Department of Applied Physics, The University of Tokyo
2012-present: Professor, Research Center for Advanced Science and Technology, The University of Tokyo
2014-present: Team Leader, Center for Emergent Matter Science, RIKEN

Quantum coherence in a single Cooper pair box
Title and affiliation when prize awarded
Senior Researcher, NEC Fundamental
Research Laboratories

Abstract when prize awarded
We demonstrated quantum coherence in a single
Cooper pair box in 1999, which was the first realisation of a superconducting qubit as well as a solid-state qubit.
We started our research on single electron transistors
in 1992. As the devices were made of aluminium,
they became superconductive at low temperatures
below 1K. Naturally, we became interested in
Cooper pair tunnelling in those devices and studied
the parity effect, which discriminates the even-odd
parity of the number of electrons in an electrode, as
well as photon-assisted Cooper pair tunnelling under
microwave irradiation around 1995-1996.
During that time, we learned the concept of macroscopic quantum coherence, coined by Tony Leggett
in 1980, and the following experimental challenges
using SQUID circuits. Macroscopic quantum tunnelling was demonstrated in the 1980s. However,coherence and superposition in macroscopic systems
had been elusive.
This led us to an experiment of quantum superposition between two distinct charge number states in
the Cooper pair box device. In 1997, we publisheda paper in Phys. Rev. Lett. on the observation of theenergy-level anti-crossing as evidence of the superposition. The result was obtained in photon-assisted
tunnelling spectroscopy.

26

20 years of the Millennium Science ForumAs a next step, we decided to do a time-domain experiment to demonstrate quantum state control of
the charge-number superposition. That was also thetime when ideas of quantum information processing
and quantum computing started to spread around thecommunity. We needed to develop a few new experimental techniques, such as the ultrafast gate-voltage
pulses for the control and the time-ensemble current
measurement for the readout, but finally succeeded
to observe coherent oscillations (Figure 1) between
charge number states, in autumn 1998. The paper
was published in Nature, in April 1999. It was well
accepted and triggered research on solid-state quantum computing.

Fig.1 Coherent oscillations observed in the first Cooper pair box
experiment.

Progress in Research
Progress in the field of quantum information sciencehas been much more rapid than what we expected in
1999. Superconducting quantum circuit technology
is one of the most advanced subjects in the field. The
coherence time of superconducting qubits, initiallyabout 1 ns and desperately short, has improved byfive orders of magnitude and is now beyond 100 μs.
On the way, we have learned a lot about physics andabout engineering of superconducting quantum circuits. The knowledge accumulated collaboratively
in the community is enormous and still growing, andmore and more groups are working in the field.
Recently, big corporations, such as Google, IBM
and Intel have been developing superconducting
quantum computers with tens of qubits. Who could
have imagined 20 years ago that everyone would be
able to use quantum computers on the cloud service?
While problems still need to be overcome before
quantum computers become useful for our society, human beings’ construction and control of suchcomplex artificial quantum systems is amazing.
I have been working continuously in the research
field since the beginning of my career. After the development of the charge qubit in NEC, I spent a year
(2001-02) as a visiting scientist at Delft Universityof Technology, in the Netherlands, where we demonstrated a flux qubit, in which a superposition of two
flux states was controlled. Around 2004, the physics of superconducting qubits evolved into the eraof circuit quantum electrodynamics (circuit QED)
through the happy marriage with quantum optics.
Circuit QED turned out to be a powerful tool bothfor fundamental studies and for quantum computing
architectures using superconducting circuits in the
microwave domain. Following successful experiments with qubits coupled to a resonator, we also
initiated waveguide QED, where qubits are coupled
to a 1D transmission line as simple realisations oftailored open quantum systems. Now, in microwave
quantum optics, we can generate and detect single
microwave photons and other non-classical states.
After I moved to The University of Tokyo and started a new research group, we began exploring a newresearch direction of hybrid quantum systems. We
used superconducting qubits as a tool for quantum
control and measurement in other physical systems,
particularly collective excitations in solid state. For
example, in quantum magnonics, we demonstrated
control and measurement of single magnons in a
millimetre-scale sphere of ferromagnetic crystal. In
quantum nanomechanics, we achieved ground-statecooling of a vibration mode of a millimetre-scale

membrane. More recently, we combined a superconducting qubit and a surface-acoustic-wave (SAW)
resonator and strongly coupled microwave photons
and SAW phonons. We are also interested in coupling those collective excitations to optical photons
in order to build a quantum interface between microwave and optical quantum information media.
Our latest focus is on the development of integrated superconducting qubits and the implementationof quantum information processing. We are aiming
at scalable architecture allowing for at least a hundred qubits. High-fidelity control and readout of thequbits are demanded.

Reflections
I would like to express my sincere gratitude andcongratulations on the 20th anniversary of the Sir
Martin Wood Prize. It has significantly influenced
and contributed to the promotion of the research incondensed matter physics in Japan. The breadth anddepth of the themes covered by the Sir Martin Wood
Prize in the last two decades represent the progressof the research fields. It was my greatest honour tobe the first prize winner, especially considering theexcellence of the winners who followed me.
It has been almost 20 years since I received the prize
from Sir Martin Wood, in 1999. Nevertheless, I vividly remember the ceremony at the British Embassy,
Tokyo as well as my visit to Sir Martin’s manor
house in Oxford. It was my first visit to the UK,
which I enjoyed very much thanks to the kind support of Professor Noboru Miura and Tony Ford. My
visit to the factory of Oxford Instruments, in Tubney
Wood, was also very exciting.
During my stay in Oxford, I bought the first volumeof the Harry Potter series. After 20 years, no one issurprised by moving pictures on the wall any more.
The evolution of science and technology is so fast.
Lack of imagination may be the only reason for impossibility, while the future is not ours to see, Que
Sera, Sera.
Lecture Trip
University of Oxford, University of Cambridge,
University of Bristol
Contact Information
yasunobu@ap.t.u-tokyo.ac.jp
20 years of the Millennium Science Forum

27

Winner in 2000

Tokushi Kizuka

Current title and affiliation
Professor, Department of Materials Science,
University of Tsukuba

1991: D.Eng. The University of Tokyo
1991-2002: Associate Professor/Lecturer, School of Engineering, Nagoya University
1998-2001: Researcher, Japan Science and Technology Corporation, Precursory Research
for Embryonic Science and Technology
2002: Associate Professor, Institute of Materials Science, University of Tsukuba.
1998-2001: Researcher, Japan Science and Technology Agency, Precursory Research for
Embryonic Science and Technology (Advanced Type)2010-present: Professor, Department of Materials Science, University of Tsukuba

Simultaneous observation of millisecond dynamics in atomistic structure,force and conductance on the basis of transmission electron microscopy insolid point contacts
Title and affiliation when prize awarded
Associate Professor/Lecturer, School ofEngineering, Nagoya University

Abstract when prize awarded

The elucidation of “structures and transformation”, i.e.,
how atoms configurate solids and how their arrangement changes, is a basic subject in condensed matterphysics. Diffraction analyses, such as X-ray methods
and various types of static microscopy, have achieved
successful outcomes for the former subject “structures,”i.e., the determination of average atomic arrangementsof solids in stable states. In contrast, these methods havenot provided sufficient contribution in the latter subject“transformation.” Structural dynamics had not been analysed at the atomic scale although it is focused on as amajor subject in a tremendous number of studies. This isbecause even if the structures are analysed in a stepwise
fashion during a process, actual structural dynamics isnever found out. As a result, continuous atomistic structural dynamics had been studied only via computational
science, as exemplified by molecular dynamics calculations. However, the calculated results could not becompared with any experimental results. The development of an innovative experimental method, which canchase the motion of individual atoms in solids as a live
broadcast from atomic worlds, had been much awaitedin condensed matter physics. Scientists and engineers inthis field had also been convinced that the experimental
results obtained from the innovative methods lead to thecreation of new devices exhibiting noble functions. During an in-situ observation, the observed structures canbe controlled. Take, for example, atomic crafts using an
in-situ observation as “an eagle eye” and the operation
as “small hands and tools.”
We developed in-situ high-resolution transmission electron microscopy (HRTEM) to observe directly atomic
motion of solids during mechanical deformation, frac28

20 years of the Millennium Science Forumture, phase transformation, surface modulation and interface formation. This developed in-situ HRTEM alsoenabled simultaneous measurements of conductance ofnanostructures and forces acting on them. In particular,
the experimental basis of the atomic-scale mechanismsof materials was established.
We applied the in-situ HRTEM to study various nanometre-sized structures and elucidated the atomistic
structural dynamics during the formation of single atom
contacts and wires, which are the finest contacts joinedby only one atom and the thinnest wires, i.e., one dimensional single atom alignments, respectively. We explicated the atomic-scale mechanisms of materials for solid
point contacts (nanometre-sized contacts), resulting in
the discovery of new deformation mechanisms of nanostructures in addition to fundamental atomic processof deformation. Other nanostructures, such as fullerene
molecules, carbon nanotubes and single-molecular junction structures, were fruitful targets of the developed
in-situ HRTEM.

Progress in Research

The awarded study has led to the following progress inresearch.
(1) Single-photon spectroscopy of individual nanostruc­tures under in-situ HRTEM
The functions of scanning near-field optical microscopy(SNOM) are installed in HRTEM for cathode- and photoluminescence spectroscopy of individual nanostructures.
An optical fibre probe, having apertures of several tens ofnanometres in width, is allowed to approach individual
nanostructures, i.e., isolated nanoparticles and nanometre
regions in polycrystals, under simultaneous structuralobservation by in-situ HRTEM. The method directly provides the relationships between atomic arrangements ofindividual nanostructures and luminescence.
(2) Free-space nanometre wiring via nanotip manipulation
Relentless efforts in semiconductor technology have
driven nanometre-scale miniaturisation of electronic devices and their interconnections. Free-space writing enables interconnections of stacked modules, leading to ultimate integration of electronics. We have developed freespace nanometre-scale wiring by manipulating a metallic
nanotip during application. The method is capable offabricating wires with widths down to 1 nm and lengths
exceeding 200 nm, with a breakdown current density of~10 TA/m2. Structural evolution and conduction during
wire formation can be analysed by direct atomistic observation using in-situ HRTEM.
(3) Control of the structures and electrical properties ofsingle molecular or nanoparticle junctions
As the miniaturisation of integrated circuits advances,electronics using single molecules and nanoparticles arebeing studied increasingly. Ultimate junctions consistingof two electrodes sandwiching a single molecule or nanoparticle are assembled by a nanotip operation duringin-situ HRTEM. We investigated the atomic configuration and conductive properties of the junctions. It was
found that the conductive properties depend on the interface structures of the contacts between the core element
and electrodes. Thus, the relationship between atomic
arrangements of the junctions and conductive properties
can be elucidated directly.
(4) Transformation from slip to plastic flow deformation
mechanism of nanometre-miniaturised metals
Various types of nanometre-sized structures have been
applied to advanced functional and structural devices.
Inherent structures, thermal stability and properties areemphasised when their size is decreased to less than several nanometres, especially, to several atoms. We discovered that such miniaturised structures are deformed via
a plastic flow mechanism, which has not been observedin coarse-grained metals. The resultant various irregularrelaxed structures exhibit noble electrical and mechanical functions. This study opens a new research field ofstructural control of metallic devices comprised of only
one or several atom(s).
(5) Surface reconstruction in nanowires
It is well-known that surface atomic positions are reconstructed due to stabilisation. Such surface reconstruction
has been conducted for general surfaces, which are larger
than the size of reconstructed surface unit cells. Hence,the surface reconstructions investigated for large surfaces are not applicable for the surfaces of nanometre-sized
isolated crystals, such as nanoclusters, nanowires andnanotubes, having high ratios of surface area to interior

volume. Also, their surface structures significantly affect their mechanical, electrical, optical and magnetic
properties. We demonstrated the inherent surface reconstruction of metallic nanowires via the in-situ HRTEM.
This study leads to evolution in basic studies relating tosurface reconstruction and in applications of nanowires
used in extremely miniaturised integrated circuits fornext-generation electronics.
In addition to the above-mentioned studies, my other original research subjects relating to, for example, atomistic
friction, single-atom sharpened needles and high-temperature thermal barrier coatings, have roots in the study recognised by the Sir Martin Wood Prize, in 2000.

Reflections

I am especially pleased to express my congratulations
on the 20th anniversary of the Sir Martin Wood Prize. I
sincerely appreciate its steering and selection committees. In particular, I acknowledge Professors Noboru
Miura and Hidetoshi Fukuyama, who were chairs ofthese committees when I was awarded the prize in 2000.
It has been almost two decades since I was awarded
the prize. At that time, Jiro Kitaura, former president of
Oxford Instruments KK, kindly explained the difficulty
and laborious efforts to establish the Millennium Science
Forum (MSF). I would like to applaud the great effortsof the committees’ members to promote the MSF for the
past 20 years.
I very much appreciate Sir Martin Wood for his warm
hospitality, especially in his house in Oxford. He showedme and Professor Katsuya Shimizu of Osaka University(my fellow prize winner in 2000) a chilling device hedeveloped when he worked in his laboratory. Tony Ford
looked after us before the award ceremony and continues
to do so even today. I thank him very much for his kind
support.
I would like to express my sincere gratitude to Emeritus Professor Ayahiko Ichimiya of Nagoya University.
He has kindly supported me since I studied at Nagoya
University, my former affiliation. He introduced many
famous scientists, including Nobel prize winners, to me,which were precious opportunities for a young scientist.
He has advised me on my research direction and guided
me in my involvement with the MSF. I owe what I am
today to him.

Lecture Trip
University of Oxford, University of Cambridge
Contact Information
kizuka@ims.tsukuba.ac.jp
20 years of the Millennium Science Forum

29

Winner in 2000

Katsuya Shimizu

Current title and affiliation
Professor, Division of Materials Physics, Graduate
School of Engineering Science, Osaka University

1989: B.E. Faculty of Engineering Science, Osaka University
1991: M.E. Graduate school of Engineering Science, Osaka University
1994: Ph.D. Osaka University
1995-1997: Research Fellow of the Japan Society for the Promotion of Science for Young Scientists
1997-2002: Research Assistant, Division of Materials Physics, Graduate School of Engineering
Science, Osaka University
2002-2003: Lecturer, Division of Materials Physics, Graduate School of Engineering Science, Osaka University
2003-present: Professor, Center for Science and Technology under Extreme Conditions, Osaka University

Search for superconductivity under ultra-high pressure
Title and affiliation when prize awarded
Lecturer, Graduate School of Engineering
Science, Osaka University

Abstract when prize awarded
We have developed techniques for measuring electrical resistance and magnetization at ultra-high pressure and at very low temperature. A diamond-anvil
cell (DAC) is popular and the most powerful tool
for producing static pressure. We have constructed
a compact non-magnetic DAC specially designed
for low temperature research. We recently attained
to perform electrical measurements above 200 GPa
at temperature down to 30 mK by assembling on a
powerful 3He/4He dilution refrigerator. The combination of two powerful tools has made it possible tostudy the condensed matter physics in unprecedentedly wide pressure-temperature range.
One of the most aggressive challenges under highpressure research is the search for metallic hydrogen
under its extremely dense phase. The metallic hydrogen is predicted to show superconductivity evenat room temperature and has long fascinated thehigh-pressure physicists, which exists in fact at theinterior of a giant planet such as Jupiter or Saturn.
Another challenge topic is “superconductivity” and“magnetism”. It is well known that a ferromagnetic
metal does not show superconductivity and even asmall amount of paramagnetic impurities could suppress the superconductivity. However, even in thecase of iron, the superconducting transition temperature (Tc) was theoretically predicted to be 0.25 K.
We can expect an appearance of superconductivity
in magnetic metals in its nonmagnetic state undercertain pressure and low temperature.
Electrical transport measurements in DAC can
30

20 years of the Millennium Science Forumprovide both the proof of metallization and superconductivity at low temperature. Conductivity measurements are difficult in general at Mbar-pressuresusing DAC because of the wiring problem to thesmall sample and insulation between the wire andthe metal gasket. We succeeded to perform a fourprobe electrical resistance measurement in DAC atpressure of 250 GPa in non-hydrostatic measurements; 10 GPa in hydrostatic ones using a ‘liquid’pressure medium where a piston-cylinder type hydrostatic cell delimitates the maximum pressure ofaround 3 or 4 GPa.
Using these experimental technique, we have studied
searching for metallization and superconductivity insimple systems such as elements like halogen atoms,
chalcogen atoms, 3d-magnetic metals, and alkaline
metals. Recently, the high-pressure research of superconductivity in heavy-fermion systems is a populararea. We also apply these technical advances to thearea where hydrostatic pressure is required since axial stress causes the dislocation which is considered tosuppress the superconductivity.

Progress in Research
Generally, "superconductivity" is known as a rare
phenomenon. Superconductivity can be seen in a
few compounds, which are made by special treatments, however here we suppose that “superconductivity” is a rather common phenomenon in generalmaterial but caused through variety of the mechanism. Can all elements be superconductive? “It has
been already revealed that several elements that arenot the superconductor at ambient pressure became
superconductive at high pressure. Actually, the number of superconducting elements at ambient pressure
is 30, and another 23 elements become superconducting at pressurized condition. Additionally, mostof superconducting materials, include elements,
show a negative pressure effect; the superconducting
transition temperature, Tc, decreases by applying
pressure. However some elements were found toshow the positive effect. Recently I have intensively
studied superconductivity in elements not only forunderstanding the mechanism of superconductivity
but also for searching the unrevealed possibility ofthe material. The new periodic table for superconductive elements is shown in Fig. 1 which claims
that elements on the upper-right and upper-left corner of the table gives higher Tc. At this moment, calcium (Ca) reaches almost 30 K, which is the highest
in elements, but it needs pressure exceeding 200
GPa.
The most attractive among various elements is hydrogen in the condensed phase as solid metallic
hydrogen is expected to be a room-temperature superconductor. Also, fluid metallic hydrogen underhigh pressure and at high temperature may provide
important information about the interior of giant
planets. However, realization of the solid metallic
hydrogen requires ultrahigh pressures exceeding 400
GPa at ambient temperature, which is still challenging for high-pressure experimentalists.

Fig. 1 Three dimension periodic table for elements. The height ofthe pillar indicates the highest Tc ever observed in each element.
On the upper-right and upper-left corner of the table, the elements
give the higher Tc. The highest Tc was observed in Ca with 29 K
at 217 GPa.

We aim to produce solid metallic hydrogen and reveal the physical phenomena with technical development and an innovative approach. The current project also aims for remarkable progress in the studyof material sciences under high-pressure by further
strengthening the application of developments.
This will reveal novel physical properties hidden inultra-high pressure and construct a new era of solid-state physics.

Reflections
Congratulations to the Sir Martin Wood Prize for20 years. It means that 20 years has passed since I
received the award and went on my lecture visit to
the UK where I got the opportunity to give lecturesat Oxford and Cambridge Universities. It was mysecond trip to the UK, the first was a two-month low
budget visit where I followed my supervisor. I was
surprised that the scale of laboratories was smaller
than expected; only a few postdocs and/or PhD students were working with a professor. They do very
good research and then move every few years and a
new research theme comes. Good research themes
will bring good researchers from around the world.
Recently fewer Japanese students want to work inoverseas groups. Is this due to a charming environment in Japanese laboratories? I would like to motivate them not only to go overseas more, but also toenjoy good research.

Lecture Trip
University of Oxford, University of Cambridge
Contact Information
shimizu@stec.es.osaka-u.ac.jp
20 years of the Millennium Science Forum

31

Winner in 2001

Keiya Shirahama

Current title and affiliation
Professor, Department of Physics,
Keio University

1985: B.S., Department of Physics, Hokkaido University
1987: M.S., Graduate School of Physics, Hokkaido University
1990: D. Sc., Graduate School of Physics, The University of Tokyo
1990: JSPS Research Fellow (ISSP, The University of Tokyo)
1991: Alexander-von-Humboldt Fellow, University of Bayreuth, Germany
1993: Research Associate, ISSP, The University of Tokyo
1999: Associate Professor, Keio University
2009-present: Professor, Keio University

Electrons meet helium: Superfluid 3He surface probed
by the Wigner crystal

Title and affiliation when prize awarded
Associate Professor, Department of Physics, Keio University

Abstract when prize awarded
Superfluid helium is the purest substance in nature.
The free surface of superfluid helium has been of
great interest as it is recognized as a surface (boundary) of topological superfluids. My research work
concerning the Sir Martin Wood Prize was the firstexperimental study of the free surface of liquid helium 3, a fermion isotope of helium, in particular in
the superfluid states.
One can trap many electrons on a free surface ofliquid helium. The electrons form a two-dimensional
system and undergo a phase transition to the Wigner
crystal with a triangular lattice. Since electrons on
helium surface was the only system that realizes
the Wigner crystal state, the interest of community
concentrated to understand its properties. With Dr.
Kimitoshi Kono at ISSP The University of Tokyo,
I explored the possibility of utilizing the crystal forthe study of helium surface. This idea was successfully proven by a series of experiments. Our earlytransport measurement of crystal on a liquid helium
3 surface showed extremely high electron mobility (μ~ 108cm2/Vsec), which is still the record of electron
mobility in condensed matters. This result not only
showed the ultra-clean nature of helium surface, butalso opened the possibility of utilizing surface electrons for quantum computing.
We succeeded to measure the mobility of the Wigner
crystal on the surface of superfluid states of helium 3
down to 200 μK. It was unexpectedly found that the32

20 years of the Millennium Science Forum

mobility is dominated by scattering of helium quasiparticles to the periodically deformed surface. Since
the quasiparticle spectrum is determined by superfluid energy gap, we can study various gap structuresof the superfluid A, B, A1 and possible new phases
and change in gap structures near the surface. The
first order transition between the A and B phases anda nonlinear transport caused by deformation of thesurface were also clearly observed.

Fig.1: An illustration of the Wigner solid on a liquid helium surface. Electrons (shown as yellow balls) form a triangular latticeand press the helium surface. The "dimples" formed beneatheach electron produce unique dynamical phenomena.

Progress in Research
Liquid helium 3 had been established as a textbook
example of anisotropic fermion superfluid. The
situation has been dramatically changing since thediscovery of topological insulators in 2006. The concept of topological insulators was applied to superfluidity and superconductivity, and superfluid helium
3 is realized as a unique topological superfluid. The
Wigner solid can be a useful probe for the topological superfluid, in which intriguing surface phenomena such as Majorana bound states are theoretically
proposed.

After winning the 2001 Sir Martin Wood Prize I continued to study the dynamics of the Wigner solid on
helium 4 and isotopic mixtures, but I have graduallyfocused my interests to the properties of superfluid
helium itself. I discovered a quantum phase transition in helium 4 under nanoscale confinement. This
discovery has lead me to utilize the confinement effect for unveiling novel topological properties of superfluid helium 3. My research group at Keio is currently conducting experiments on superfluid helium
4 and 3 in well-defined nano/microscale confinedgeometries and pursuing to search for superfluidity
in adsorbed films other than helium.

UK is the birthplace of the low temperature physics
when Sir Martin showed me the first superconducting magnet made by them.
I would like to thank the Sir Martin Wood Prizecommittee, staff of Oxford Instruments, and myfriends and colleagues in the UK who made thelecture trip successful. Last but not least, I would
like to thank Professors Miura and Fukuyama, andMr.Tony Ford, for their continual supports and encouragement to me since winning the prize.

Reflections
Let me write my personal recollection of the Sir
Martin Wood Prize ceremony and the following lecture trip. Two weeks before the Ceremony I broke
my ankle by slipping on the stairs of Shimokitazawa
Station. I almost gave up to attend the ceremony as I
was in hospital until a few days beforehand. Eventually I could attend the ceremony with crutches, andsomehow gave the prize lecture sitting on a special
stage. I was happy that Sir Martin directly awarded
me the Prize. I was also pleased that the speakerafter me was Dr. Mamoru Mohri, the first Japanese
astronaut, because I grew up in the town next to hisbirthplace in Hokkaido and he has been my herosince the first astronaut selection in Japan.
On the lecture trip, I gave talks at Manchester, Royal Holloway and Oxford. At that time, Powerpoint
presentation was rapidly spreading and I was the first
person to use Powerpoint for the prize lecture. In myfinal lecture in the Martin Wood Lecture Theatre of
Oxford, I broke into a cold sweat just a few minutes
before the start time as the presentation slide did notappear on the screen of the theatre (it was a common
problem then). I felt that my presentation got betteras I repeated the same lecture in three universities. I
was impressed by some of the famous low temperature physicists who attended my lecture: the UK
is the birthplace of low temperature physics, and I
remembered the names of Dewar, Simon, Mendelssohn, Kurti and others.
The visit to Oxford Instruments and the time spent
with Sir Martin and Audrey in their Manor House
were also unforgettable. Again, I realized that the

Lecture Trip
University of Manchester, University of Oxford,
Royal Holloway, University of London
Contact Information
keiya@phys.keio.ac.jp
20 years of the Millennium Science Forum

33

Winner in 2002

Ichiro Terasaki

Current title and affiliation
Professor, Department of Physics,
Nagoya University

1986: B.S., The University of Tokyo
1988: M.S., The University of Tokyo
1988-1990: Doctorate Course, The University of Tokyo
1990-1993: Research Associate, The University of Tokyo
1992: Doctor (Engineering)
1993-1997: Chief Researcher, International Superconductivity Technology Center
1997-2003: Associate Professor, Waseda University
2003-2010: Professor, Waseda University
2004: Visiting Professor, University of Bristol
2010-present: Professor, Nagoya University
2015-present: Cross-Appointment Fellow, National Institute of Advanced Industrial Science and Technology (AIST)

Large thermopower in NaCo2O4 : a novel physical property
in transition-metal oxides
Title and affiliation when prize awarded

Associate Professor, Department of Applied
Physics, Waseda University

Abstract when prize awarded
We discovered a large thermopower and anomalous
properties in the layered cobalt oxide NaCo2O4 in the
study of reference materials concerning high-temperature superconductors (HTSC). This study has
accelerated the research field of oxide thermoelectrics: the energy conversion technology between
heat and electricity using oxide ceramics.
The discovery of high-temperature superconductivity in copper oxides, in 1986, has made two great
impacts on basic science. One is to deny the superstition that only a mega-science can discover new
physics. The other is to remove the wall between
physics and chemistry; physicists have begun to synthesise many samples, and chemists have begun tomeasure physical properties very precisely. I am one
such physicist, who makes samples, measures properties precisely, and thinks deeply about the meaningof the measured data.
NaCo2O4 is an old material, which was synthesised
and identified in the 1970s by French chemists. We
succeeded in making single crystals and measured
the resistivity and thermopower (voltage proportional to the applied temperature difference). We foundthat the measured values were as good as those forthe state-of-the-art thermoelectric material Bi2Te3
and reported a possibility that NaCo2O4 was applicable to thermoelectric devices.
This made a great impact to the community because
34

20 years of the Millennium Science Forumthe common thought at that time was that oxides
were too poor to be used for thermoelectric devices.
We tried to uncover the secret of this oxide, and finally arrived at the concept that the magnetism andelectron-electron interaction were crucial. This idea
had not been considered in thermoelectric materials
thus far.
Chemists are eager to make many new materials andidentify their structures. Once they have done so,they are often satisfied and leave other properties
untouched. The high thermoelectric performance in
NaCo2O4 is a prime example, and I believe that thisindicates the raison d’être of physicists developing
new materials. We physicists can find interesting anduseful functions which have been sleeping quietly in
old materials that chemists synthesised a long timeago. Post-HTSC physicists, including myself, will
search for new functions in existing materials rather
than in new materials.

Progress in Research
As oxide thermoelectrics has been developed widely, as of July 2018, our discovery paper has received
more than 2,700 citations, according to Google
Scholar. In the meantime, applications using thermoelectric oxides have been developed, and a venturecompany named TES New Energy, which sells oxide thermoelectric power generators spun out from
AIST. I am a happy scientist because what I foundhas been accepted by my scientific peers and has
been used in practical devices by engineers.

Later, TES New Energy developed a cooking panequipped with a thermoelectric power generator. It
was named Hatsuden-Nabe, (which means electricity-generating pan). This product became popular andwas distributed in a village in Uganda by a non-governmental organisation. In the village, no electric
power is supplied, so residents cannot do anything
but sleep after dinner. The Hatsuden-Nabe with LED
diode gave them light at night, and high school students looked happy because they could study at theirclassroom in the evening. When I heard of this news,
I felt that a small scientific discovery may be able
to make our future a bit better. Unfortunately, TES
New Energy ceased manufacturing, but many photos
and videos are still available on the web (search for
Hatsuden-Nabe).
I have continued to search for new functions in oldmaterials. My next discovery was to observe a giant
non-ohmic resistance in an organic conductor. The
organic sample showed a resistance 1,000-times
smaller simply by changing the current from 1 μA
to 10 mA. This discovery has been developed as a“non-linear conduction in strongly correlated electrons,” and has attracted keen theoretical interest
from researchers of string theory and statisticalphysics.
On a cold, wintry day, we see ponds freeze whilerivers are flowing. Electrons in solids behave similarly; they are frozen as an ordered state, but the order may be melted by an electron flow, i.e. externalcurrent.
Finding new materials or, to be precise, finding
new functions is a dialogue with a sample. Whenever I talk to the sample through measurement of aquantity, it always replies through the signal for themeasurement. Analysing the reply, I ponder deeply
on what property is being kept waiting for measurement. Then I talk to the sample once more througha different measurement, and it replies again. Using
this method, the feedback loop is really great fun tome; it shows me that nature is rich, fertile, and profound. This is the best moment, I feel, to be a scientist.

Reflections
I would like to express my sincere gratitude andcongratulations on the 20th anniversary of the Sir

Martin Wood Prize.
When I was awarded the Sir Martin Wood Prize in
2002, it was the first time I had won a prize in mylife. Definitely, it launched my career. I would liketo sincerely thank Sir Martin Wood, Professor Noboru Miura, Tony Ford and many others for supporting
this prize.
Although 16 years have passed since I won, I remember clearly the lecture trip I took in autumn
2003 as part of the prize. I visited the University ofBristol for the first time and decided I would takesabbatical leave there in 2004. I’ll also never forget
the delightful chats I had with Tony, who kindly
drove us to the universities we visited. During thedrive to Oxford from Cambridge, in the evening, we
saw many fireworks quietly lighting up the dark sky
in various places. It was Guy Fawkes Night.
It was a pity that we did not have the chance to visit
the home of Sir Martin Wood, but my wife and I
thoroughly enjoyed the lecture trip, including our
experience of culture in the UK.

Fig.1: Dinner in a restaurant near Oxford during the lecture visit

Lecture Trip
University of Bristol, University of Cambridge,
University of Oxford, Cardiff University
Contact Information
terra@nagoya-u.jp
20 years of the Millennium Science Forum

35

Winner in 2003

Toshimasa Fujisawa

Current title and affiliation
Professor, Department of Physics,
Tokyo Institute of Technology

1986: B.S. Department of Applied Physics, School of Science, Tokyo Institute of Technology
1991: Ph.D. Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology
1991-2008: NTT Basic Research Laboratories
2008-present: Professor, Tokyo Institute of Technology

Single-electron dynamics in semiconductor quantum dots
Title and affiliation when prize awarded
Senior Research Scientist, NTT Basic Research Laboratories

Abstract when prize awarded

Electrons play important roles in many systems.
Nanotechnology allowed us to manipulate single
electrons one by one and provided unique systems
in which dynamic behaviour of single electrons canbe studied. In this work, “Single-electron dynamics
in semiconductor quantum dots,” single electron
dynamics were successfully tailored and measured
precisely in a relatively short timescale.
Single-electron ammeter: A quantum dot is a small
conductive island, in which tuneable numbers ofelectrons occupy discrete energy levels. Electronstransport through the dot one by one in the single-electron tunnelling regime. Each tunnelling
event can be monitored
by a sensitive charge
detector. We have successfully developed asingle-electron ammeterthat can measure extremely small current on
the order of atto-amperes with a single-electron resolution. The single-electron ammeter can be applied
to various fields that require high sensitivity andhigh accuracy in electrical current.
Semiconductor charge qubit: A double quantum
dot provides a tuneable
quantum two-level system that can be used asa quantum bit (qubit)
for quantum computing.
We have successfully
demonstrated full one36

20 years of the Millennium Science Forum

qubit operations with rotation and phase-shift gate
in a semiconductor double quantum dot. By applying a voltage pulse, coherent oscillations of a single
electron between the two dots were successfully
induced. Furthermore, two-qubit operations including controlled-NOT gate and swap gate have beensuccessfully demonstrated.
Long spin lifetime: An electron spin in a quantum
dot is also attractive as a qubit for its long spin relaxation time. We have developed an electrical pumpand-probe scheme toinvestigate the long spin
lifetime. The scheme
is now widely used tomeasure spin lifetime invarious quantum dots.
The series of works on
single-electron dynamics in semiconductor quantum
dots has stimulated subsequent developments in nano-electronics and quantum computing.

Progress in Research
The works on single-electron dynamics in semiconductor quantum dots were extended for studying
charge dynamics in low-dimensional semiconductors.
In contrast to zero-dimensional states in quantum
dots, one- and two-dimensional electronic systems
have kinetic degrees of freedom, but they are quite
different from those in ordinary three-dimensional
systems. The low-dimensional systems are particularly interesting for studying non-trivial quasiparticles.
We focus on mostly dynamics in the quantum Hall
effect of a two-dimensional electron system under astrong magnetic field. While the central region (bulk)

is insulating (a kind of topological insulator), one-dimensional electrical channels are formed along theboundary between the bulk and the outer region (vacuum). Intriguing characteristics of low-dimensional
electrons can be studied in the system.
One-dimensional chiral plasmons: Electron-electron scattering associated with Coulomb repulsion
alters the transport characteristics in one-dimensional
conductors. Based on the Tomonaga-Luttinger model, spin and charge degrees of freedom propagate indifferent manners in one-dimensional conductors,
known as spin-charge separation. Previously, suchsignatures were detected in the power-law anomaly
in the electron transport characteristics. As the theory
suggests, such an anomaly can be understood mo­reeasily in terms of plasmons, which are quasiparticle
excitations originally called spinon and holon. We
have demonstrated clearly how the spin and charge
degrees of freedom are separated in a time-resolved
measurement. Furthermore, the Tomonaga-Luttinger
model, known as
an exactly solvablemodel, suggests thepresence of many
conserved quantities and the absenceof thermalisation
processes in the system. This is attractive for transporting massive information in the one-dimensional
channel. We have successfully observed non-thermal
metastable states in our recent experiment.
Electron-phonon hybrid system: Coupling of electrons to phonons has been known to cause scatteringor energy relaxation in semiconductors. This negative effect can be applied in a constructive way torealise an acoustic analogue of cavity quantum electrodynamics (cQED). We have successfully fabricated an electron-phonon hybrid system, in which a
double quantum dot is embedded in a phonon cavity
for surface acoustic waves (SAW) on a GaAs/AlGaAs heterostructure. The phonon-assisted transport
is significantly enhanced at the resonant frequency.
This is attractive for studying strong or ultra-strong
coupling regimes.
Electron-phonon hybrid system: Coupling of electrons to phonons has been known to cause scatteringor energy relaxation in semiconductors. This negative effect can be applied in a constructive way torealise an acoustic analogue of cavity quantum elec-

trodynamics (cQED).
We have successfully
fabricated an electron-phonon hybrid system, in which a double
quantum dot is embedded in a phonon cavity
for surface acoustic waves (SAW) on a GaAs/AlGaAs heterostructure. The phonon-assisted transport
is significantly enhanced at the resonant frequency.
This is attractive for studying strong or ultra-strong
coupling regimes.

Reflections
When I was an undergraduate student, I was quite
impressed with a charge coupled device (CCD), notas an image sensor but as an intriguing transfer action of charges in a queue. I was excited by the electric control of electrons. This was one of the reasons
why I started studying semiconductor physics on a
graduate course and, later, single electron dynamics.
Semiconductor nanostructures are fascinating playgrounds, with electrons for engineers as well as
physicists. One can tailor a potential profile in sucha way that electrons travel through a narrow passage(quantum point contact), a few electrons are packed
in a container (quantum dot), and electrons move in
one direction (quantum Hall edge channel).
I was also excited about more advanced control ofelectrons with single-electron accuracy. At a lowtemperature, electron motion is dominated by quantum mechanics, where the particle-wave duality
shows up. Moreover, interacting electrons exhibit
non-trivial motions. In this way, techniques for controlling electrons have been developed considerably
for a few decades. Now, a natural question is what
we can use this advanced technology for. It would benice to have a meaningful application of intriguing
electron features in our life. I hope some young scientists will be inspired to extend the work and find areal application.
Lecture Trip
University of Cambridge, University of Nottingham,
University of Oxford, University of Southampton
Contact Information
http://fujisawa.phys.titech.ac.jp/
20 years of the Millennium Science Forum

37

Winner in 2004

Yuzo Ohno

Current title and affiliation
Professor, Faculty of Pure and Applied
Sciences, University of Tsukuba

1991: B.S. Department of Electronics Engineering, The University of Tokyo
1993: M.S. Department of Electronics Engineering, The University of Tokyo
1996: D. Eng., Department of Electronics Engineering, The University of Tokyo
1996-2001: Research Assistant, Research Institute of Electrical Communication, Tohoku University
2001-2012: Associate Professor, Research Institute of Electrical Communication, Tohoku University
2012-present: Professor, Faculty of Pure and Applied Sciences, University of Tsukuba

Spin injection and spin control in semiconductors
Title and affiliation when prize awarded
Associate Professor, Research Institute of ElectricalCommunication, Tohoku University

Abstract when prize awarded
In order to demonstrate spin injection into semiconductors, we fabricated light emitting diodes (LEDs)
which consist of pn junctions of a p-type ferromagnetic semiconductor (Ga,Mn)As and non-magnetic
n-GaAs with a strained (In,Ga)As quantum well
(QW) inserted as an active region. Here, p-type(Ga,Mn)As is used as a spin polariser: Spin-polarisation of the injected holes is determined directly fromthe electroluminescence (EL) polarisation emitted
after the recombination with unpolarized electrons
according to the optical selection rule. EL is collected from the cleaved facet to minimise magneto-optical effects due to the nearby (Ga,Mn)As, and its polarisation was investigated with a variable magnetic
field applied parallel to the easy axis of the (Ga,Mn)
As layer, i.e. in Faraday configuration. We observedthat the EL polarisation below TC draws a clear hysteresis loop: the remanence EL polarisation at zeromagnetic field is about 1% at T = 6 K. It follows
the magnetization of (Ga,Mn)As, which is independently measured by a Superconducting Quantum
Interference Device (SQUID) type of magnetometer.
The presence of hysteretic EL polarisation indicatesthat the hole spins can be injected and transported in
non-magnetic GaAs.
Injection of spin polarized electrons, not holes, ismore preferable from the application point of view
as electrons usually exhibit longer spin lifetime due
to small spin-orbit coupling. Because of the lack ofn-type ferromagnetic semiconductor, we employed38

20 years of the Millennium Science Foruma spin Esaki diode and demonstrated electrical electron spin injection from the valence band of a p-type
ferromagnetic semiconductor (Ga,Mn)As into the
conduction band of a non-magnetic semiconductor
via interband tunneling. Clear hysteresis loop with
±6.5% remanence is observed in the magnetic fielddependence of EL polarization from an integratedp-(Ga,Mn)As/n-GaAs/(In,Ga)As/p-GaAs LED.
We also investigated electron spin dynamics in
GaAs/AlGaAs QWs grown on (110)-oriented substrates with n-doping, in which the spin relaxation
mechanism predominant for conventional (100)QWs is shown to be substantially suppressed. It wasdemonstrated that the spin relaxation time is found
to reach nanosecond order in wide temperature
range by optical time-resolved measurements. This
has enabled us to investigate nuclear spin dynamics
by optically detected nuclear magnetic resonance.

Progress in Research
As for the research of spin injection, we investigatedinjection of spin polarized electrons in a (Ga,Mn)As∕n+-GaAs Esaki diode (ED) by using a three-terminal device integrating a (Ga,Mn)As ED and alight emitting diode (LED). Electroluminescence polarization (PEL) from the LED was measured under
the Faraday configuration as a function of bias voltages applied independently to the Esaki diode and to
the LED. The maximum PEL of 32.4% was observed
when the valence electrons near the Fermi energy of(Ga,Mn)As are ballistically injected into the LED.

We also directly measured the spatiotemporal evolution of photoinjected local spins of a two dimensional electron gas in a modulation-doped GaAs/AlGaAsquantum well with a top gate electrode by using atime- and spatially resolved Kerr microscopy. The
spatial pattern of spins after diffusion is controlled
by a gate voltage that changes the strength of thespin-orbit interaction (SOI) field. By measuring thetime dependence of spin distribution with an external magnetic field, we successfully observe a persistent spin helix state by tuning the gate voltage andobtain both Rashba and Dresselhauss SOI parameters separately.
As for the research on spin coherence in GaAs (110)QWs, we demonstrate manipulation of nuclear
spin coherence in a GaAs/AlGaAs quantum wellby optically detected nuclear magnetic resonance(NMR). A phase shift of the Larmor precession ofphotoexcited electron spins is detected to read out
the hyperfine-coupled nuclear spin polarization.
Multipulse NMR sequences are generated to control
the population and examine the phase coherence inquadrupolar-split spin-3/2 75As nuclei. The phase coherence among the multilevel nuclear spin states isaddressed by application of pulse sequences that areused in quantum gate operations.

ternal magnetic field with respect to the QW plane.
It is likely that the non-uniform EFG as well as thehyperfine interaction governs the inhomogeneous
broadening of NMR spectra.

Reflections
I would like to express my sincere congratulations
on the 20th anniversary of the Sir Martin Wood Prizeawarded by the Millennium Science Forum.
The Sir Martin Wood Prize is a unique prize in termsof the grateful opportunity to give a lecture in famous UK universities, it was a precious experience
for me to improve my presentation skills in English.
During my visit to the University of Oxford, in addition
to meeting faculty staff, I came in touch with the historical culture of the UK, which is a great incentive
for young researchers in Japan.
I would like to express my sincere thanks to Professor Noboru Miura and Tony Ford for their kind support during my visit in the UK.

We also demonstrated electrical coherent manipulation of a quadrupolar-split nuclear spin ensemble ina GaAs quantum well (QW) with an rf electric fieldby the optical time-resolved Kerr rotation technique.
Rabi oscillations and phase control between two
spin-3/2 states are demonstrated by nuclear electricresonance in a gated GaAs QW device. This enables
us to achieve coherent control of geometrically specified nuclear spins.
Furthermore, we obtained strain and electric field
gradient (EFG) in an n-GaAs/Al 0.3Ga 0.7As (110)quantum well (QW) by optically detected nuclear
magnetic resonance (NMR). The dependence ofthe quadrupolar splitting on an angle between the
QW plane and a static magnetic field provided the
crystalline-orientation-dependent EFG and strain
in the GaAs QW. We also explored the dependenceof the NMR line widths on the direction of the ex-

Lecture Trip
University of Sheffield, University of Cambridge,
University of Oxford, University of Southampton
Contact Information
oono@bk.tsukuba.ac.jp

http://www.bk.tsukuba.ac.jp/~oono/

20 years of the Millennium Science Forum

39

Winner in 2005

Tsuyoshi Kimura

Current title and affiliation
Professor, Graduate School of Frontier
Sciences, The University of Tokyo

1991: B.E. Synthetic Chemistry, The University of Tokyo
1993: M.E., Superconductivity, The University of Tokyo
1996: Ph. D, Superconductivity, The University of Tokyo
1996-2000: Postdoc, Joint Research Center for Atom Technology
2000-2003: Lecturer, Dept. of Applied Physics, The University of Tokyo
2003-2005: Limited term staff member, Los Alamos National Laboratory, United States
2005-2007: Member of technical staff, Bell Laboratories, Lucent Technologies, United States
2007-2017: Professor, Graduate School of Engineering Science, Osaka University
2017-present: Professor, Graduate School of Frontier Sciences, The University of Tokyo

Materials design toward gigantic magnetoelectric response
Title and affiliation when prize awarded
Member of Technical Staff, Lucent Technologies,
Bell Laboratories (USA)

Abstract when prize awarded
Ferromagnets develop a spontaneous magnetisationthat is sensitive to an external magnetic field; in asimilar fashion, the spontaneous polarisation in ferroelectric materials depends on an external electricfield. The study of these systems encompasses a considerable portion of condensed matter physics. Thesematerials also figure prominently in recent electronic
devices. However, these two collective properties(ferromagnetism and ferroelectricity) have been
investigated mainly as distinct and independent phenomena. One of the coupling phenomena between
magnetism and ferroelectricity is the “magnetoelectric effect”, that is, the induction of magnetisation
by means of an electric field and that of an electric
polarisation by means of a magnetic field. This phenomenon attracted some interest in the 1960s and
70s, as the effect can provide an additional degreeof freedom in device design. However, there havebeen no applications using the magnetoelectric effect, mainly due to material limitations. Given large
magnetic (electric) responses to an external magnetic (electric) field in ferromagnetic (ferroelectric)
materials, one approach to achieving a large magnetoelectric response is the use of materials in which
ferromagnetic and ferroelectric orders exist simultaneously. Such materials are called “multiferroics.”
We have explored novel multiferroics showing gigantic magnetoelectric responses. Consequently,
perovskite-type rare-earth manganese oxides including TbMnO3 were found to exhibit ferroelectricity
40

20 years of the Millennium Science Forumaccompanied by an unexpected spiral magnetic
order [1]. By using these compounds, we observed
a gigantic magnetoelectric effect, that is, a control of the magnitude and direction of an electric
polarisation vector by applying a magnetic field.
Furthermore, we proposed that frustrated magnets
possessing complex magnetic structures, such as aspiral magnetic structure (Figure), can be promising
candidates for multiferroics with gigantic magnetoelectric effects. Based on these materials’ design
strategy, we found that some other transition-metaloxides with spiral magnetic orders exhibit remarkable magnetoelectric couplings [2]. Our discovery
has provided a new route to design materials showing ferroelectricity with magnetic origin as well asgigantic magnetoelectric responses.
[1] T. Kimura et al. Nature 426, 55 (2003).
[2] T. Kimura et al. Phys. Rev. Lett. 94, 137201 (2005).

Figure : Spiral magnetic structure which breaks inversion symmetry and results in ferroelectricity.

Progress in Research
After our discovery of the giant magnetoelectriceffect in TbMnO3, studies on magnetoelectric couplings and multiferroics have gained renewed interest in the community of materials science and con-densed matter physics. Under such circumstances,
we have been seeking new magnetoelectric phenomena and materials with higher performances, including high-temperature operation and the magnitude ofthe effect.
In terms of the magnitude of the magnetoelectriceffect, we revealed that TbMnO3 exhibits a pressure-induced magnetoelectric phase transition andthat the high-pressure phase shows the largest ferroelectric polarisation among magnetically induced
ferroelectrics ever reported. Moreover, the ferroelectric polarisation is further enhanced by applying
a magnetic field. Its magnitude is comparable to thatof conventional ferroelectrics. These results demonstrate that it is possible to attain giant spin-driven
ferroelectric polarisation, which comes close to thatin conventional displacive ferroelectrics, and to control it magnetically.
One of our major achievements in terms ofhigh-temperature operation is the discovery of alow-field magnetoelectric effect at room temperature
in some hexaferrites whose crystal structures are
similar to ferrite magnet (refrigerator magnet). We
demonstrated a magnetic control of ferroelectric polarisation up to about 400 Kelvin, for the first time,in a Z-type hexaferrite Sr3Co2Fe24O41. Non-volatileelectric-field control of magnetism at room temperature was also demonstrated in these hexaferrites.
More recently, we achieved a magnetic-field controlof electric polarisation at room temperature in a liquid crystal with a chiral smectic structure. Thus, thestudy of magnetoelectric couplings is not limited toinorganic transition-metal oxides.
Since the concept of symmetry breakings is critical in magnetoelectric coupling phenomena, weare expanding our study in this context. We are
exploiting materials possessing magnetoelectriccluster-multipoles breaking both time-reversal andspace-inversion symmetries, which is a requirement of a linear magnetoelectric effect. Examples
of such cluster multipoles are magnetic toroidal andmagnetic quadrupole moments. We designed andsynthesized materials involving these multipoles,
and experimentally demonstrated their presence andmagnetoelectric activities in some transition-metal compounds such as toroidal-glass (Ni,Mn)TiO3
and ferro magnetic quadrupolar Pb(TiO)Cu4(PO4)4.
Apart from magnetic multipole moments, we suc-ceeded in observing the symmetry breaking due tothe helix chiral motif of electric quadrupole moments and its domain structure in enantiomorphic
DyFe3(BO3)4 with Dy 4f electric quadrupoles.

Reflections
Congratulations on the 20th anniversary of the Sir
Martin Wood Prize! I would like to convey my gratitude to those who have contributed to its activities.
I had just joined Lucent Technologies, Bell Laboratories, New Jersey when I received the notice that I
had won the Sir Martin Wood Prize. Looking at thelist of past prize winners, I find that I am the only
winner who belonged to a foreign research institutewhen the prize was awarded. I was lucky that the
prize is not restricted to researchers in Japanese institutes, rather it includes all those whose work is
performed in Japan.
A uniqueness of the prize is that a lecture trip to the
UK is provided to the recipient. Various experiences
including not only scientific events but also social
ones, to experience British culture during the trip
were quite enjoyable and memorable. I remember that
we stopped in a suburban restaurant and enjoyed fish
and chips when travelling from Cambridge to Oxford
in a car driven by Tony Ford. Another uniqueness isthe abundant opportunities to interact with other prize
winners. From 2011, the MSF has held a Sir Martin
Wood Prize lecture at Osaka every December. I enjoyed hosting and listening to one of these lectures
when I was in Osaka University. Through this opportunity, I was able to chat with not only a new winner
but also former recipients every year.
In my opinion, the best part of being awarded theprize is having more opportunities to meet various
people, which is by far more valuable than a cash
prize. I appreciate the Millennium Science Forumfor giving me such priceless opportunities and believe that I have to do that for young researchers.
Finally, I would like to thank all of my colleagues,
students, and collaborators for their kind support.
Lecture Trip
University of Cambridge, University College London, University of Oxford, University of Warwick
Contact Information
tkimura@edu.k.u-tokyo.ac.jp
20 years of the Millennium Science Forum

41

Winner in 2006

Kazutomo Suenaga

Current title and affiliation
Prime senior researcher : National Institute ofAdvanced Industrial Science and Technologies

1994: D. Eng., Department of Materials Science, The University of Tokyo
1994-1997: Post-doc, Centre des Materiaux, Ecole Nationale Superier de Mines, France
1997-1998: Post-doc, Solid State Physics Laboratory, University of Paris-Sud, France
1998-2001: Researcher, ICORP Nanotubulites project, Japan Science and Technology Agency (JST)2011-present: Team leader/Prime senior researcher, National Institute of Advanced Industrial Scienceand Technology
2015-present: Visiting Professor, Department of Mechanical Engineering, The University of Tokyo

Electron microscopy and spectroscopy on single molecules
Title and affiliation when prize awarded
Team Leader, National Institute of Advanced
Industrial Science and Technologies

Abstract when prize awarded
Imaging and identification of single atoms/molecules is an ultimate goal of all analytical techniques.
In 2000, we reported the first successful elemental identification of individual atoms by means ofelectron spectroscopy [1]. It came 200 years after
the establishment, at the end of the 18th century, of
Dalton’s atomic theory, which first proposed distinct
elements among atoms [2].
Advances of nanotechnology increasingly rely on
the advancement of atomic technologies and therefore the progress of electron microscopies, which
are capable of visualising and analysing constituent
atoms in individual nanostructures. Electron spectroscopy based on a scanning transmission electron
microscope equipped with an energy-loss spectrometer enables us to obtain the chemical compositionof individual quantum objects with high sensitivity
and high resolution, which are crucial to detect dopants or impurities in materials at atomic level.
Also, a phase contrast of high-resolution transmission electron microscopy with high time resolution
and high sensitivity allows dynamic observationof individual atoms and visualisation of individual
molecular structures. Point defects such as vacancies
and pentagons, as well as the Frenkel pair defects
in carbon nanotubes, can be also visualised duringformation and annihilation. This work highlights
our achievements in atomic-scale characterisation ofindividual nanostructures, involving the individual42

20 years of the Millennium Science Forum

molecular imaging, the single atom spectroscopy
and the point defect detection.
[1] K. Suenaga et al., Science 290 (2000) 2280
[2] J. Dalton, A New System of Chemical Philosophy, byRussell, (1808)

Fig. : The first report of single-atom EELS. (Left) The specimen
was Gd@C82 metallofullerenes encapsulated in single-walledcarbon nanotubes. (Bottom) EELS spectra recorded on Gd atomic sites shows the signal of Gd M-edge. (Right) The constructedchemical maps for Gd, for carbon, and a color map (red:Ge,
blue:carbon).

Progress in Research
Since 2006, I have been more interested in the development of instrumentation because I realised thatthe electron microscope must have more potential
to sense individual atoms in nanostructures. Witha Japanese manufacturer we started two national
projects supported by JST in order to develop highperformance transmission electron microscopes(TEM/STEM) with geometric and chromatic aberra-Fig. : Single atom spectroscopy of dopants in graphene. (a) Cr atom at the graphene edge, (b)Fe atom at di-vacancy, and (c) L2,3core-level EELS clearly indicates that both Cr atom atedge (up) and Fe atom at di-vacancy (bottom) show a high-spin state.

tion corrections. Lowering the accelerating voltage
of TEM/STEM turned out to be essential when one
aims to image any e-beam sensitive object. Observation of small molecules made of light elements,
in particular, requires a reduced accelerating voltage, to avoid destroying the molecular structuresdue to knock-on effects and to enhance the image/
EELS contrast. To compensate for the poorer spatial
resolution, more sophisticated electron optics are
required for the low voltage TEM/STEM, to reduce
the residual geometric/chromatic aberrations [1].
Thanks to the projects, the possibilities of single-atom spectroscopy have been extended widely.
Information on the bonding/electronic states has become accessible for single atoms through the EELS
fine-structure analysis as well as the spin state [2].
Large variations of local electronic properties of 1D
and 2D materials with different atomic coordinateshave been revealed. Such an analysis was used tounderstand catalytic behaviour of Co doped MoS2
for a hydrodeoxygenation reaction as an example ofpractical applications [3]. Furthermore, a high-energy resolution EELS offers us new possibilities toobtain local optical/vibrational properties.

and candidates selected for the Sir Martin Wood
Prize.
I still remember very well my lecture trip to the UK
in 2006. We visited my old friends in Oxford, Leeds,
Surrey and Cambridge. A most impressive event
during the trip was a dinner at St Anne’s College,
Oxford, which began with grace, delivered in Latin
by Professor Andrew Briggs. It was a great experience for a young Japanese researcher like me toexperience such a British custom for the first time.
Another moving occasion was my visit to Sir Martin
Wood at his home. We had a promenade together
in the large garden, followed by morning tea withscones and jams made by his wife, Audrey. They
were so delicious and unforgettable to us. I have not
had a chance to see Sir Martin and Audrey for a longtime and hope to have another chance to see themsoon.

[1] H. Sawada et al., Phys. Rev. Lett., 114 (2015) 166102[2] Y.C. Lin et al., Phys. Rev. Lett., 115 (2015) 206803[3] G. Liu et al., Nature Chemistry 9 (2017) 810-816

Reflections
I would like to congratulate the Sir Martin Wood
Prize on its 20th anniversary. I would like to express
my appreciation to the secretariat of the forum, without whose devoted support success would not havebeen possible, as well as to the steering committee

Lecture Trip
University College London, University of Cambridge,
University of Surrey, University of Oxford, University of Leeds
Contact Information
suenaga-kazu@aist.go.jp
20 years of the Millennium Science Forum43

Winner in 2007

Akira Ohtomo

Current title and affiliation
Professor, Department of Chemical Science andEngineering, Tokyo Institute of Technology

Akira Ohtomo was born in 1972. He studied materials science at Tokyo Institute of Technology andgot a doctoral degree of engineering in 2000. After two years postdoc at Bell labs, he moved to Tohoku University in 2002. In 2009, he returned to Tokyo Institute of Technology and initiated his ownlaboratory. He has published over 180 papers, which are cited over 19,000 times (h-index 59).

High-mobility electron gas at polar oxide heterointerfaces
Title and affiliation when prize awarded
Associate Professor, Institute for Materials
Research, Tohoku University

Abstract when prize awarded
Atomic-scale control of oxide heteroepitaxy is of
growing importance from the viewpoints of both
fundamental physics and device applications. Many
intriguing physical phenomena such as high-Tc superconductivity, ferromagnetism, ferroelectricity,and thermoelectricity occur in naturally layered
structures of transition metal oxides, giving rise to
emergent interests for “epitaxial” design of newcompounds upon the atomic-scale layer-by-layer
growth of artificial superlattices.
We developed an ultra-high vacuum-pulsed laser
deposition system equipped with reflection high-energy electron diffraction. In this system, rapid optimisation of the growth temperature can be carriedout by using an infrared semiconductor laser heaterthat makes a large temperature gradient, enabling
to realise atomically abrupt heterointerfaces andnearly identical oxygen stoichiometry. Using thistechnique, we studied magnetotransport propertiesof high-mobility electrons at polar oxide heterointerfaces. In the first case, we created a metallic statein an atomically abrupt heterointerface between
two band insulators, SrTiO3 and LaAlO3, in which
naturally arising polarity discontinuity introduces
high-mobility electrons in SrTiO3. As a result, dramatic magnetoresistance oscillations appeared at
low temperatures. Rotation angle dependence of theoscillations in the magnetic field suggested three-dimensionality of the conducting electrons. Second,
we fabricated ZnO/MgZnO heterostructures to attain44

20 years of the Millennium Science Forumsufficiently high electron mobility to observe thequantum Hall-effect. In this case, two-dimensional
electron gas (2DEG) was formed in the heterointerfaces due to strong built-in potential arising from aspontaneous polarisation mismatch. The density of
2DEG could be controlled in a wide range by tuning
the Mg content in the MgZnO barriers.
These results have implications for all oxide heterointerfaces, including magnetic tunnel junctions,
Josephson junctions, oxides on semiconductors, etc.
In particular, the high mobilities achieved present
the possibility to combine the world of oxides (superconductors, multiferroics, colossal magnetoresistance) with the world of semiconductor heterostructures, including quantum Hall physics. This
work is also a demonstration of the power of the
field of nanoscience to create new physical phenomena. This and other recently developed techniques totailor new materials, atom-by-atom, should continue
to reveal new effects at an ever-accelerating pace.

Progress in Research
Recent advances in the epitaxial growth of metal oxides enable to demonstrate various thin-film devices
for applications of advanced computing and renewable energy production. Transition-metal oxides, suchas TiO2 and α-Fe2O3, are conventional materials utilised as anodes for photoelectrochemical (PEC) water splitting because their non-toxic, earth abundant,
and stable nature are advantageous to PEC reactions.
Our recent research interest is to add new function-

alities to them by combining the power of epitaxial
growth techniques and electrochemical redox reactions. Well-defined thin films with a flat surface andhigh crystallinity provide ideal platforms for investigating intrinsic effects arising from the modulationof compositions, orientation, stoichiometry, and/or
electronic states. Moreover, there has been continued focus on controlling competition between Mott/
Peierls insulators and correlated metals, because
novel phenomena such as superconductivity andmetal-insulator transition often emerge at the phaseboundaries. We have made progress on iron for ironoxides and titanium oxides. Starting preparationof source materials, pulsed laser deposition was
conducted on selected substrates under various conditions. We also implemented a compact PEC celland a Li-ion secondary battery structure. Our recent
achievements are summarised as follows. (1) bandgap narrowing in solid solutions films of α-Fe2O3
and Cr2O3, and orientation control of α-Fe2O3 films
resulted in substantial improvement of visible-lightdriven PEC water oxidations. (2) Complete and reversible superconductor-insulator transitions in LiT2O4 films could be induced by Li-ion electrochemical reactions [1]. (3) Superconductivity of Ti4O7 andγ-Ti3O5 films, with the transition temperatures of 3.0
K and 7.1 K, respectively, was observed despite theinsulating ground states in their bulks [2]. This approach is a powerful way to find new functionalities
of materials for sustainable society.
[1] K. Yoshimatsu, M. Niwa, H. Mashiko, T. Oshima, A.
Ohtomo, Sci. Rep., 2015, 5, 16325.
[2] K. Yoshimatsu, O. Sakata, A. Ohtomo, Sci. Rep.,
2017, 7, 12544.

the prize. He gave me a great opportunity, to be asupervisor at both Tokyo Institute of Technology andTohoku University.
I’m very happy to be a winner of the Sir Martin
Wood prize. I have achieved many things in the 10
years since I received the prize. First, I was promoted to my current position at Tokyo Institute ofTechnology. Then I received the JSPS Prize fromthe Japan Society for the Promotion of Science and
the Gottfried Wagener Prize from the German Innovation Award, based on my achievements evaluatedby prize selection committee. My family and I werepleased that my achievements were honoured withthese prizes. At the same time, the Sir Martin Woodprize gave me great confidence as a faculty member
teaching the next generation of researchers.
I’m grateful to Professor Noboru Miura and Professor Fukuyama for accompanying me on my lecture
trip to the UK, which was truly my real prize. Theygave me guidance on how I could give a lecture in
front of a large number of students and researchers,in such a way that I did not feel overly tense or panicin response to unexpected questions. Also, from thebottom of my heart I thank Tony Ford, who organised and facilitated the lecture itinerary, which I was
glad to experience.
Thanks to everyone involved in the prize, including
those I could not mention, my every working day
is busy. I’m so sorry that I cannot participate in the
ceremony to which I’m invited every year, but I
wish for further progress of the MSF and the professors on the selection committee.

Reflections
I would like to express my heartfelt gratitude to theMillennium Science Forum (MSF). The Sir Martin
Wood Prize, which is marking its 20th anniversary,is widely recognised as a way of promoting young
researchers studying condensed matter science.
I think that promotion is thanks to the efforts of
Oxford Instruments KK and Professor Hidetoshi
Fukuyama as well as other professors sitting on the
Sir Martin Wood Prize selection committee. I would
like to thank Professor Masashi Kawasaki, whojoined the selection committee after I was awarded

Lecture Trip
University College London, University of Sheffield,
University of Oxford, University of Cambridge
Contact Information
aohtomo@apc.titech.ac.jp
20 years of the Millennium Science Forum45

Winner in 2008

Teruo Ono

Current title and affiliation
Professor, Institute for Chemical
Research, Kyoto University

1991: B.S. Faculty of Science, Kyoto University
1993: M.S. Graduate School of Science, Kyoto University
1996: Ph.D. Graduate School of Science, Kyoto University
1996-1997: Japan Society for the Promotion of Science Postdoctoral Fellow
1997-2000: Assistant Professor, Faculty of Science and Technology, Keio University
2000-2002: Lecturer, Graduate School of Engineering Science, Osaka University
2002-2004: Associate Professor, Graduate School of Engineering Science, Osaka University
2004-present: Professor, Institute for Chemical Research, Kyoto University

Control of magnetisation in nano-magnets by electric current
Title and affiliation when prize awarded
Professor, Institute for Chemical Research, Kyoto University

Abstract when prize awarded
It is well known that ferromagnets show the magneto-resistance effect, i.e. the resistivity in ferromagnets
depends on the relative angle between the directionof magnetisation and the electrical current. Thus,
magnetisation controls the flow of the electricalcurrent. We explored the possibility of the reversed
phenomena, i.e. control of magnetisation by electric
current.
We demonstrated this concept using nano-magnets(magnetic wire or magnetic disk). A magnetic domain wall (DW) exists between two opposite magnetisations (blue and red arrows) in a magnetic wire
(Fig.1 (a)). It was found that the injection of electrical current through the wire successfully displaced
the DW (Fig.1 (a)-(c)). This current-induced domain
DW motion is considered to be a kind of magnetic
excitation by a current that flows through a spin
structure with spatial variation (DW). This concept
has been tested for another typical noncollinear spin
structure: a magnetic vortex. Figure 2 shows a perspective view of the magnetisation with a moving
vortex structure. The height is proportional to theout-of-plane magnetisation component. The rainbow
colour indicates the in-plane component as exemplified by the white arrows. On application of theAC current though the magnetic disk, the core starts
to make a circular orbital motion around the disk
centre, and finally the magnetisation of the core flips
into the reversed direction.
The electrical control of magnetisation described isvery efficient and scalable down to the nano world,46

20 years of the Millennium Science Forumas it is based on the quantum mechanical interaction
between the flowing spins and the localised spinsthat constitute magnetisation. It is therefore a key
technology for future spintronic devices. In fact,
IBM proposed a novel storage device called “racetrack memory,” whose operation relies on the current-induced DW motion.

Fig. 1: MFM observation of current-induced DW motion.

Fig. 2: Current-induced switching of vortex core in magnetic disk.

Progress in Research
Rotating magnetic disks (hard disk drives (HDDs))
and semiconductor memories such as static anddynamic random-access memories (SRAMs andDRAMs) have for many years served as the bedrock technologies for the processor caches, main
memory, and secondary storage in computers. Theircontinued use, however, poses problems with regard
to energy consumption. The most critical problem
with semiconductor memories is volatility; the information they store is lost whenever the computer’s
power supply is turned off. They require constant
power just to retain the stored information. There is
therefore a strong demand for non-volatile memory
devices. HDDs are also energy-consuming devices.
Although their huge capacity and low cost makethem indispensable in our daily life, the mechanicalmotion required in their operation not only resultsin the danger of head crashes and other mechanicalfailures but also wastes energy. Current computersthus use energy even when they are not working andcan therefore be called normally-ON computers. A
normally-OFF computer, or one that uses energy
only when doing calculations, is still only a dream.
We made pioneering contributions to the realisationof this dream by demonstrating the basic operationof two kinds of non-volatile magnetic devices: racetrack memory and magnetic vortex core memory.
Fig. 3 shows the demonstration of the principle operation of racetrack memory. DWs created by the
local magnetic field induced by a current flowing in
the writing wire were reproducibly shifted, keeping

the distance between them, by the current injected
into the magnetic wire. The DWs were also shiftedback and forth depending on the direction of theinjected currents. We also demonstrated an all-electrical operation of the magnetic vortex core memory
cell by using a three-terminal device in which thetunnelling magnetoresistance junction is integrated onto a ferromagnetic disk (Fig. 4). Binary data
corresponding to the core direction can be read out
electrically as the amplitude of the device output andwritten electrically by applying a pulsed current.

Fig. 4: Demonstration of an all-electrical operation of the magnetic vortex core memory cell.

Reflections
It is my great honour to provide this message as
one of the winners of the Sir Martin Wood Prize. I
would like to thank all the people who led me to thewonderful world of science. Although the possibilityof technological applications is emphasised here, I
would like to stress that these achievements haveoriginated from fundamental studies on the interaction between conduction electron spins and local
magnetisations. I think all technologies are built on
the solid basis of fundamental science that has beencreated fundamentally by the pure scientific interestsof individuals.

Lecture Trip
University of Oxford, University of York, University College London, University of Cambridge

Fig. 3: Demonstration of racetrack memory.

Contact Information
ono@scl.kyoto-u.ac.jp
20 years of the Millennium Science Forum47

Winner in 2008
Current title and affiliation
Professor, Department of Applied
Physics, The University of Tokyo

Eiji Saitoh

1996: B.S. in Applied Physics, The University of Tokyo
1998: M.S. in Applied Physics, The University of Tokyo
2001: Ph.D. in Applied Physics, The University of Tokyo
2001-2006: Assistant Professor at Department of Physics, Keio University
2006-2009: Lecturer at Department of Applied Physics, Keio University
2009-2018: Professor at Institute for Materials Research,Tohoku University
2012-2018: Professor, Principal Investigator, WPI-AIMR,Tohoku University
2014-present: Research Director, ERATO (JST)2018-present: Professor,Dept. of Applied Physics, The University of Tokyo

Discovery of inverse Spin-Hall and Spin-Seebeck effects
Title and affiliation when prize awarded
Assistant Professor at Department of Physics, Keio University

Abstract when prize awarded
We discovered phenomena to detect spin current.
Spin current refers to a flow of electron spin angular momentum in condensed matter, which is a spin
analogue of electric current. An electron is a particle
which carries two quantities: electric charge andinternal autorotation called a spin. Spin informationis quite fragile in condensed matter; in fact it disappears within a very short length scale, such as one
thousandth of 1mm in Cu. So, it used to be unimportant. However, this length scale is no longer negligible today; contemporary electronic devices are composed of nanometer-scale structures, much smaller
than the spin disappearance length scale. In such asmall world, spin current and electric current should
be considered on equal footing. However, althoughphysics of electric current in matter is well written
in the electromagnetism in matter, no laws were
provided for spin current (macroscopic effective
theory for spin current was missing); which meansthat there was no compass to search for spin current
phenomena. Our work was the finding of a series offundamental phenomena of spin current. In particular, the discovery of inverse spin Hall effects [1], thegeneration of electric fields from spin current, mademeasurements of spin current possible. By using
the effect as a spin-current probe, we then exploredphysical phenomena induced by spin current. One
typical outcome is the discovery of the spin Seebeck
effect [2] in YIG/Pt: the conversion of heat current
into spin current. Surprisingly, we found spin current
can flow even in insulators such as YIG when spin
48

20 years of the Millennium Science Forum

excitation gap in the insulators is small enough [3].
[1] E. Saitoh et al. Appl. Phys. Lett. 88 (2006) 182509.
[2] K. Uchida et al. Nature 455 (2008) 778-781.
[3] Y. Kajiwara et al. Nature 464 (2010) 262-266.

(a)

(b)

(c)

Fig. 1:(a) Conduction electron spin current(b) Two-particle model of inverse spin Hall effect (ISHE)(c) Electric-field generation from spin current via ISHE.

Progress in Research
After the Sir Martin Wood Prize in 2008, our findings were recognized as the beginning of the spincurrent experimental science. The inverse spin Halleffect established itself as a standard spin-current detection method. The effect has been used all over theworld, and so many phenomena were found basedon it, such as sound-induced, light-induced, and mechanical motion-induced spin current generation.
The spin Seebeck effect is now used as one of themost standard methods for spin-current generation,
and YIG/Pt became a standard spintronics material
system most frequently used in spintronics experiments. Some companies have tried to apply the spin
Seebeck effect to make thermoelectric convertors
to generate electricity from environmental heat. Recently, spin current physics is being expanded fromcondensed matter science into nano-fluid science, nano-mechanical science, and also into hadron physics.
[4] “Spin current” 2nd edition, Oxford University Press(2017).
[5] “Spin current and topological insulators”, Kyoritsu
shuppan (2014).
(a)

(b)

(c)

Reflections
I would like to express my sincere gratitude and mycongratulations to the 20th anniversary of the Sir
Martin Wood Prize. The prize ceremony and the trip
I had are my cherished and unforgettable memories.
I deeply appreciate the members of the selection
committee of Sir Martin Wood Prize and the Millennium Science Forum.
Spintronics is an interdisciplinary field composedof physics, electronics, and material science, providing a role model for productive collaboration
among different fields. In electronics, there was agreat demand for non-volatile memory devices withultralow-energy consumption, which was necessary
to break-through the wall of energy consumption
problems in computer industries. From the materialscience point of view, there was an established fieldon magnetic materials.
The emergence of nanotechnology made it possible
to combine these to make devices, but the generalprinciple and concept to create new device functions
were still missing. Condensed matter physics playeda significant role in such a situation; physics researches explored and systematize new phenomena,and gave a guiding principle to find out undiscovered phenomena and materials. This was indispensable to establishing the field.
I hope that young researchers in condensed matterscience have a broad vision and play an active partvigorously to create new fields. Last but certainly
not least, I would like to thank my collaborators on
this project, Prof. S. Maekawa, Prof. G.E.W Bauer,
their group members, and our students and graduates, especially Dr. K. Ando, Dr. K. Uchida, Dr. Y.
Kajiwara, and Dr. Y. Shiomi.

Lecture Trip
University of Oxford, University of York, University College London, University of Cambridge
Fig. 2:(a) Spin current generation from sound waves and phonons(b) Fluid spin -current generation(c) Electronics mechanism of fluid spin-current generation

Contact Information
eizi@ap.t.u-tokyo.ac.jp
20 years of the Millennium Science Forum49

Winner in 2009
Current title and affiliation
Chief Scientist, Director of Surface and Interface Science Laboratory, RIKEN

Yousoo Kim

1991: B.S., Department of Chemistry, Seoul National University (South Korea)
1993: M.S., Department of Chemistry, Seoul National University (South Korea)
1999: D. Eng. Department of Applied Chemistry, The University of Tokyo
1999-2002: Special Postdoctoral Researcher, Surface Chemistry Laboratory, RIKEN
2002-2006: Research Scientist, Surface Chemistry Laboratory, RIKEN
2006-2009: Senior Research Scientist, Surface Chemistry Laboratory, RIKEN
2010-2015: Associate Chief Scientist, Surface and Interface Science Laboratory, RIKEN
2015-present: Chief Scientist, Surface and Interface Science Laboratory, RIKEN

When a molecule meets electrons
Title and affiliation when prize awarded
Senior Research Scientist, Surface Chemistry
Laboratory, RIKEN

Abstract when prize awarded
The study of single molecules provides deep insights
into the nature of bonding and underlying quantum
mechanics concerning the control of chemical reactions. The scanning tunnelling microscope (STM) isa versatile and powerful tool for investigating andcontrolling the chemistry of individual moleculeson solid surfaces. The most important feature of the
STM is that the tunnelling electrons are involved in
its operation. The coupling of tunnelling electrons
with the electronic and vibrational states of the target molecule allows us to realise mode-selective
and state-selective chemistry of the individual molecules.
I will address two main issues with our experimental
and theoretical efforts on investigating the interaction of electrons with vibrational and electronic
states of a single molecule on surfaces. The first partis assigned to the excitation of vibrational modes toselectively induce particular dynamic motion andchemical reaction of a single molecule on metal surfaces. The microscopic mechanism of vibrationallyinduced molecular motions and the selection rules
for the single-molecule vibrational spectroscopy
are also discussed. A precise control of molecularmotions and chemical reaction by exciting vibrational modes with an STM will also be explained(Figure(a)). The second part focuses on the novel reaction dynamics of a single molecule on an ultrathin
insulating film surface. The ultrathin insulating film
decouples the molecular orbitals from the metallic
substrate, to prevent electronic quenching of the ex50

20 years of the Millennium Science Forumcited molecule, resulting in a much longer lifetimeof excited states, which enable the exploration ofnovel reaction dynamics of molecules. Here, I show
selective control of reaction pathways of a single
water molecule on an MgO ultrathin film grown ona silver single crystal surface (Figure(b)).

“Figure (a) A schematic figure of vibrational excitation of a single
molecule by injecting tunnelling electrons from the STM tip, andthe STM images measured before and after single-molecule reaction by vibrational excitation [Phys. Rev. Lett. 89 (2002) 126104].
(b) Electron injection from the STM into a target molecule on
the surface of 2-ML MgO film grown on Ag(100), and the dissociation pathways of a single water molecule [Nature Materials 9(2010) 442].”Progress in Research
My life work is to describe details of energetic processes, such as energy conversion, transfer and dissipation, in a single molecule on solid surfaces by useof single-molecule spectroscopies mainly based on ascanning tunnelling microscope (STM).
My research achievements, which were the main
reason I was awarded the Sir Martin Wood Prize
were the investigation of single-molecule surface
dynamics resulting from the excitation of molecularvibration by tunnelling electrons from the STM tip.
In 2010, the year after I was awarded the Sir Martin
Wood Prize, I launched my laboratory in RIKEN
and started the development of a new STM facility
combined with optical excitation/detection systems
to explore electronically excited states and photochemical reactions of a single-molecule. Recently,
with my colleagues, I successfully accomplishedthe construction of the photon-STM systems andreported (1) Development of single-molecule luminescence/absorption spectroscopy [Phys. Rev. Lett.
119 (2017) 013901], (2) Visualization of energy
transfer between two molecules [Nature 538 (2016)364], (3) Photochemical reaction by excitation withvisible light [J. Am. Chem. Soc. 139 (2017) 3115],and (4) First demonstration of single-molecule
chemical reaction by use of localised surface plasmon [Science 360 (2018) 521]. Development of thenovel nanospectroscopic methodologies opens a new
way of closely looking at how energy is converted,transferred and demised at various kinds of molecular interfaces and surfaces by visualising geometric/
electronic structures at atomic/molecular level. We
are making further challenges to cover a wider range
of energy and time domains simultaneously.

series of lectures in the UK, not only at five universities but also at The Royal Society. Professor Noboru
Miura and Tony Ford were with me throughout thelecture trip. I cannot express how much I appreciatethem for their kind arrangement of the visits and forsharing good times and conversation with me.
I am very proud to have been awarded the Sir Martin Wood Prize even though I am not Japanese; thisshows the diversity and inclusion in the scientificcommunity and the Millennium Science Forum.
One of my greatest experiences during the lecture
trip was visiting the house of Sir Martin Wood. He
showed us a small and old superconducting magnet
unit that he made with his wife, Audrey, more than
40 years ago. He told us about his great partnership with Audrey during the long history of Oxford
Instruments. From our conversation, I learned theimportance of diversity, especially gender and nationality, in the scientific, engineering and industrial
communities. I strongly expect a woman to win the
Sir Martin Wood Prize in the very near future.

Reflections
I would like to congratulate the Millennium Science
Forum (MSF) on the 20th anniversary of the Sir
Martin Wood Prize. One cannot admire enough thegreat contribution by the MSF and Sir Martin Wood
Prize to the facilitation and promotion of condensed
matter physics in Japan, especially by encouraging
young scientists and bilateral cooperation within scientific communities in Japan and the UK.
As a prize winner, it was my great honour to give a

Lecture Trip
University of Liverpool, University of Nottingham,
University of Warwick, University of Oxford, University College London, The Royal Society
Contact Information
http://www.riken.go.jp/Kimlab/index.html
20 years of the Millennium Science Forum

51

Winner in 2010

Shuichi Murakami

Current title and affiliation Professor, Department of Physics, Tokyo Institute of Technology,
Professor, TIES, Tokyo Institute of Technology

1993: B.S. Department of Physics, The University of Tokyo
1995: M.S. Department of Physics, The University of Tokyo
1996-2007: Research Associate, The University of Tokyo
1999: Ph.D. Department of Physics, The University of Tokyo
1999-2000: Visiting Research Associate, Stanford University (USA)
2007-2012: Associate Professor, Tokyo Institute of Technology
2007-2011: Research Scientist, PRESTO, Japan Science and Technology Agency
2012-: Professor, Department of Physics, Tokyo Institute of Technology
2012-: Professor, TIES, Tokyo Institute of Technology

Theory of the spin Hall effect
Title and affiliation when prize awarded
Associate Professor, Department of Physics,
Tokyo Institute of Technology

Abstract when prize awarded
The new field of electronics using the spin degreeof freedom is called spintronics. The fundamental
question in spintronics is how to operate spins andinduce spin current in solids. Because the spin carries magnetism, a naïve way to produce a spin current is to use a ferromagnet.
In my research, I propose another way of producing
a spin current in solids, but without a magnetic field.
I address our theoretical proposal for intrinsic spin
Hall effect (SHE), where an external electric field
induces a transverse spin current in semiconductors
and metals as shown in Fig. 1. This is caused by the“Berry phase in momentum space,” based on the
wave nature of electrons. Since our theoretical proposal, this effect has been observed in various semiconductors and metals. The most prominent among
them is platinum, where the SHE survives even atroom temperature. This prominent SHE in platinum
can be understood from its band structure. This effectenables us to inject or detect spin current in metals
and semiconductors with a simple setup and has already been used as an experimental tool for characterising spin-transport properties of various materials.
Because the wave nature of electrons is necessary
for the SHE, one can expect a similar effect forother types of waves such as light (electromagneticwave). We find that the SHE of light appears where
the refractive index varies spatially. In the case ofinterface between different media, this SHE appears
as the Imbert shift, i.e. the transverse shift at the interface (Fig. 2).
52

20 years of the Millennium Science Forum

Another topic of recent interest, which arose fromthe SHE, is quantum spin Hall (QSH) systems (topological insulators). In QSH systems, the bulk isgapped and insulating, while the edge or surface
states are gapless and carry spin current. We proposed that bismuth ultrathin film is a good candidate
for the QSH system. This prediction has opened theway for the experimental discovery of Bi1-xSbx as athree-dimensional topological insulator.

Fig.1 Schematic figure of the spin Hall effect.

Fig.2 Imbert shift: an example for the spin Hall effect of light

Progress in Research
The central fields of my research are condensed matter theories on topological phases and spintronics.
In the field of topological phases, we have been trying to invent new concepts and combine them with

real materials. Our proposal, in 2006, that the bismuth ultrathin film is a two-dimensional topologicalinsulator, is one of the earliest proposals of topological materials. It was experimentally verified in
2013. Furthermore, I invented the concept of Weyl
semimetals, through the study of phase transitions
between a topological insulator and a normal insulator. I showed, in 2007, that the Weyl nodes in three
dimensions must be stable and therefore should
also exist in real materials. This proposal had notbeen paid much attention, until the paper by Wan etal., in 2011, on the existence of Fermi arc surface
states. Now the Weyl semimetals are a hot topic,
both in theories and experiments on topologicalmaterials. Furthermore, we have been collaboratingwith researchers in the first-principle calculations
to propose new topological materials. For example, we showed that Te (tellurium) becomes a Weyl
semimetal at higher pressure, and that Ca (calcium)
becomes a nodal-line semimetal at higher pressure.
In the field of spintronics, we have been trying topropose new phenomena from theoretical viewpoints. After our theoretical proposal of the spin Hall
effect, we theoretically proposed topological magnonic crystal, where magnons have a gap in the bulk
but support topological chiral edge modes in the gap,
similar to those in the quantum Hall system. In this
proposal we focus on the dipolar interaction between
magnetic moments, because the typical length scale
for the dipolar interaction is micrometres, which iswithin state-of-the-art fabrication techniques. We
proposed several structures of topological magnonic
crystals by combining two different ferromagnets,
or by putting ferromagnetic dots, both in a spatiallyperiodic way. We also reformulated the theory ofmagnon thermal Hall effect and derived a new formula for the thermal Hall conductivity of magnons.
Our formula serves as a standard formula for calculating this effect. We also theoretically proposed
new variants of the Edelstein effect. The Edelsteineffect refers to the phenomenon where the current in
the system induces spin polarisation due to the spinsplit bands of the crystal. In contrast, we found thata current induces an orbital magnetisation when the
crystal has a chiral structure. We also showed that
this effect is anomalously enhanced from its classicalanalogue, a solenoid. We call this effect an orbital
Edelstein effect.

Reflections
I congratulate the Millennium Science Forum (MSF)
on the 20th anniversary of its Sir Martin Wood Prizeand express my sincere gratitude to its committee
members and staff for their continuous efforts. It is
my great pleasure to see outstanding, young award
winners every year.
I have been trying to theoretically propose new phenomena that can be observed in real materials. Luckily, various phenomena that I proposed have beenverified experimentally, which is a great pleasure tome. My research field is mainly model calculations
in condensed matter theory. Model calculations
may sound easy; indeed, that thought is partiallytrue because once a model is constructed, it is often
straightforward to calculate its physical properties.
The most difficult part is to build simple models that
capture novel properties of condensed materials. It
is not at all a simple task, because the models should
be simple for calculations but, at the same time, sufficiently general to cover a broad range of materials.
I believe that good theories should be simple andbeautiful. I think I have managed to build some simple theories in condensed matter physics in someof my work, such as the proposal of the spin Hall
effect, the prediction on the bilayer bismuth thin film
as a two-dimensional topological insulator, and the
proposal of the Weyl semimetal in condensed materials. In the future, I will continue to work in thisdirection, to explore new directions in condensed
matter physics.
I would like to thank my collaborators and supervisors,
especially Professor Naoto Nagaosa and Professor
Shoucheng Zhang for their advice, encouragement
and scientific discussion. I am also grateful to thestudents and staff in my lab for their continuous collaboration and support. Last, but not least, I would
like to thank my wife, children, and parents for theircontinuous encouragement and support.
Lecture Trip
Lancaster University, University of Nottingham,
University of Oxford, University of Manchester,
University College London
Contact Information
murakami@stat.phys.titech.ac.jp
20 years of the Millennium Science Forum

53

Winner in 2011

Yukio Kawano

Current title and affiliation Associate Professor, Laboratory for Future Interdisciplinary Research of Scienceand Technology, Tokyo Institute of Technology

1996: B.S. Department of Basic Science, The University of Tokyo
1998: M.S. Department of Basic Science, The University of Tokyo
2001: Ph.D. Department of Basic Science, The University of Tokyo
2001-2006: Assistant Professor, Department of Physics, The University of Tokyo
2006-2011: Research Scientist, RIKEN
2011-2016: Associate Professor, Quantum Nano-electronics Research Center, Tokyo Institute ofTechnology
2016-present: Associate Professor, Laboratory for Future Interdisciplinary Research of Science andTechnology, Tokyo Institute of Technology

Terahertz wave detection based on low-dimensional
electron systems
Title and affiliation when prize awarded

Associate Professor, Quantum Nano-electronics
Research Center, Tokyo Institute of Technology

Abstract when prize awarded
Sensing and imaging with terahertz (THz) waves isan active area in modern optical science and technology. The advantageous properties of terahertz (THz)waves, such as the important energy spectrum in themeV range, enable various applications of imaging
and spectroscopy. However, since the THz region is
located between electronic and photonic bands, evenbasic components like detector and source have notbeen fully established, compared to other frequency
regions. The THz wave also has the problem of low
imaging resolution, which results from a much longer
wavelength than that of the visible light. By employing nanoelectronic materials and devices based on
a carbon nanotube (CNT), graphene, and a two-dimensional electron gas (2DEG) in a semiconductor
heterostructure, we developed novel types of THz
sensing and imaging devices:
1) THz-photon sensor with a CNT/2DEG hybrid device
In order to achieve highly sensitive THz detection,
we studied THz response of a CNT/2DEG hybrid
device. The utilization of this device structure enabled the detection of THz photons.
2) Near-field THz imager with sub-wavelength resolution
The development of near-field THz imaging had
been hindered by the lack of high transmission wave
line and the low sensitivity of commonly used detectors. We produced a newly designed THz near-field
imager, in which all the components: an aperture, aprobe, and a detector are integrated on one semicon54

20 years of the Millennium Science Forum

ductor chip. The development of this device allowed
us to achieve sub-wavelength resolution for the
wavelength of 100-300 µm. Electronic and molecular structures of quantum semiconductors, plasmonic
devices, and polymers were visualized with this imaging device.
3) Wide-band, frequency-selective THz spectrometer with graphene
We succeeded in observing THz photoconductivityof Dirac fermions in graphene, ranging over a wide
frequency band of 0.8-33 THz. This result demonstrated that the graphene device works as a wideband, frequency-selective THz spectrometer. We
also imaged potential fluctuations in the graphenedevice, suggesting the strong relation to the THz
photoconductivity.
Our technologies and findings provided new insights
into low-energy and low-frequency dynamics inphysics and chemistry.

Progress in Research
I am proceeding with THz science and technology
research. Our recent major achievements are the developments of carbon-based THz flexible cameras[1-3] and plasmon-based near-field spectroscopic
imagers [4,5].
Most real objects have various three-dimensional
curvatures; however, conventional THz imaging systems are mainly restricted to flat samples, hampering
accurate measurements of such curved objects. We
have recently developed a wideband, flexible andwearable THz camera based on an array of CNT
THz detectors, which has enabled multi-view THz

inspections without using bulky systems. This newimaging technology has been achieved based on (1)thermal device design for enhancement in camera
performance such as sensitivity, detection speed,
and spatial resolution, (2) microscale free-standing
CNT film arrays, and (3) a gate-free tunable doping
technology based on a variable-concentration dopant
solution.
Plasmonic structures are useful for evanescent-field
detection and analysis thanks to their outstanding
properties of high field enhancement and concentration in a subwavelength region. In spite of large
availabilities, a main shortcoming of existing plasmonic devices is that they never show resonant frequency tunability for fixed structures, which limits
the usable range of THz-plasmon-based applications.
We have developed multi-frequency-resonanceplasmonic structures and have applied them to solid-state physics research and medical examination,
including visualization of electron injection into aquantum Hall conductor and spectroscopic analysis
of mouse organs. Our techniques can be used effectively for THz sensing and imaging over a broad
range of length scales from nanometre to metre.
[1]D. Suzuki, S. Oda, and Y. Kawano, Nature Photonics
10, 809-814 (2016).
[2]D. Suzuki, Y. Ochiai, and Y. Kawano, ACS Omega 3,
3540–3547 (2018).
[3]D. Suzuki, Y. Ochiai, Y. Nakagawa, Y. Kuwahara, T.
Saito, and Y. Kawano, ACS Applied Nano Materials 1,
2469–2475 (2018).
[4]Y. Kawano, IEEE Transactions on Terahertz Scienceand Technology 6, 356-364 (2016). (Invited paper)[5]T. Iguchi, T. Sugaya, and Y. Kawano, Applied Physics
Letters 110, 151105-1-4 (2017).

Reflections
I would like to express my sincere gratitude on the20th anniversary of the Sir Martin Wood Prize. It was
my great honor to receive one of the highest-level
prizes in condensed-matter science. Encouraged byreceiving this prestigious prize, I have been pushing
forward my successive research activities.
I started my research career from the study on semiconductor physics, especially the quantum Hall
effect. My interest gradually shifted to terahertz
waves, but my focus was also on the basics of sol-

id-state physics and devices including semiconductors, CNTs, and graphene. As a result I have been
engaging in nanoscale THz science and technology
inspired by condensed-matter physics. I strongly
feel that science and engineering are closely linked.
I have enjoyed challenging an unknown field andpursuing the possibility of new fundamentals andapplications. Therefore I believe that collaboration
across academic fields to deepen one's own research
fields and discover new areas contributes to the future development of science.
I have work experience in both universities andresearch institutes. Looking back on my career, fortunately I was always in a free environment where
there were no walls between research fields. I was
encouraged to discuss with scientists in different
fields. This experience taught me how important
open mindedness to different cultures and values is
to open up a new field. I am currently collaboratingwith a medical doctor, even though I was afraid
to go to a hospital in my childhood! I believe thatanybody can change unless they put limits on theirpotential.
The various prize events provided me with tremendously stimulating experiences. In particular, thelecture trip to the UK had a significant impact on
me. I was so impressed by the story behind the invention of superconducting magnets by Sir Martin
Wood. I was told that he strived to wind superconducting wires at a time when there were no magnetic
resonance imaging instruments. This story always
reminds me of one of the most important attitudes
as a researcher: simply and honestly follow our own
interests and passions. This should lead us to successful results.
I am sure that this unique and prestigious prize
will further stimulate young researchers in condensed-matter science. I would like to express mycongratulations once again to Sir Martin Wood,
the Millennium Science Forum, and the committee
members, and wish further success in their activities.
Lecture Trip
University of Cambridge, University of Manchester,
University of Oxford, University College London
Contact Information
kawano@pe.titech.ac.jp
20 years of the Millennium Science Forum

55

Winner in 2012
Current title and affiliation
Associate Professor, Department of Applied
Physics, The University of Tokyo
2000: B.S. Department of Electronic Engineering, Tohoku University
2001: M.S. Department of Electronic Engineering, Tohoku University
2004: Ph.D. Department of Electronic Engineering, Tohoku University
2004-2008: Researcher, Japan Science and Technology Agency’s Exploratory Research for Advanced
Technology
2008-2012: Assistant Professor, Institute for Chemical Research, Kyoto University
2010-2014: Researcher, Japan Science and Technology Agency’s Precursory Research for Embryonic
Science and Technology
2012: Associate Professor, Institute for Chemical Research, Kyoto University
2013-present: Associate Professor, Department of Applied Physics, The University of Tokyo

Daichi Chiba

Electric field-induced ferromagnetic phase transition
in semiconductors and metals
Title and affiliation when prize awarded

Associate Professor, Institute for Chemical
Research, Kyoto University

Abstract when prize awarded
Electrical control of magnetism adds a new dimension to future spin-based information processing
methods. Use of an electric field instead of an electric current is expected to make ultra-low power
driving devices possible. Ferromagnetic semiconductors had been the central material for this kindof research because their magnetic properties are afunction of the carrier concentration.
We have reported, for the first time, on the electricfield control of the ferromagnetic phase transition
and tuning of the Curie temperature using (In,Mn)
As in 2000, a ferromagnetic semiconductor [1]. We
also reported, in 2003, an electric field-induced coercivity change, and an electric-field assisted magnetisation switching was demonstrated by using it[2]. We also demonstrated, in 2008, that the magnetisation direction can be manipulated by electricallycontrolling the magnetic anisotropy of (Ga,Mn)As[3]. These efforts open up an entirely new route forelectrical magnetisation switching without usinga magnetic field or current. Although one of the
problems had been a low Curie temperature of theferromagnetic semiconductors, after our findings theelectric field-induced change in magnetic properties
using ferromagnetic ultra-thin metals even at room
temperature has been reported [4-9]. Using ferromagnetic ultra-thin metallic cobalt, we realised theelectric field-induced ferromagnetic phase transition
around room temperature [7,8].
I will show the experimental results of electric field
control of various ferromagnetic properties in field
56

20 years of the Millennium Science Forumeffect structures with a channel made of III-V ferromagnetic semiconductors or 3d ferromagnetic transition metals.
I would like to thank H. Ohno, T. Ono, T. Dietl, F.
Matsukura, K. Kobayashi, S. Ono, and members of
Ohno and Ono labs for their help.
[1] H. Ohno and D. Chiba et al., Nature 408, 944 (2000).
[2] D. Chiba, M. Yamanouchi, F. Matsukura, and H.
Ohno, Science 301, 943 (2003).
[3] D Chiba et al., Nature 455, 515 (2008).
[4] M. Weisheit at al., Science 315, 349 (2007).
[5] T. Maruyama et al., Nature Nanotechnol. 4, 158(2009).
[6] M. Endo et al., Appl. Phys. Lett. 96, 212503 (2010).
[7] D. Chiba et al., Nature Mater. 10, 853 (2011).
[8] K. Shimamura and D. Chiba et al., Appl. Phys. Lett.
100, 122402 (2012).
[9] D. Chiba et al., Nature Comm. 3, 888 (2012).

Progress in Research
We have focused continuously on the control ofmagnetism in materials. We have found that themagnetic moment induced in a non-magnetic material (Pd or Pt) can be modulated by an electric field
application [10,11]. The results have led to deeper
understanding of the physics behind the effect. From
the application viewpoint, we have shown that even
the Faraday effect can be switched based on electricfield-induced ferromagnetic transition in Co [12].
Using this technique, we demonstrated that thetransmitted light can be switched on and off. This

may be useful as a miniaturised optical switch inan optical integrated circuit. We have also proposedthat the electric field-induced phase transition canrealise a domain wiring in a magnetic race track [13].
In this demonstration, we used a magnetic track witha ferromagnetic gate electrode. In this device, themagnetisation of the gated area returns to the same
direction as that of the ferromagnetic gate electrodeowing to its stray field when the ferromagnetism of
the gated area is restored by turning off an electricfield. Thus, writing operation can be realised simply
by switching an electric field on and off without any
Oersted field application or current injection. In thisstructure, the domain writing is only one way, but
the reversed domain can be shifted by the electricalcurrent injection into the magnetic track. Therefore,
the information can be written repeatedly.
We have also worked on integrating spintronics andflexible electronics. We have been able to detect nota magnitude but a direction of strain using a giant
magnetoresistive (GMR) device fabricated on a flexible substrate [14]. The GMR device with strain-sensitive and insensitive ferromagnetic layers separated
by a non-magnetic layer was used to realise this. I
believe that the integration of spintronics and flexible electronics will establish a novel interdisciplinary research field based on science and engineering.
[10] A. Obinata and D. Chiba et al., Scientific Rep. 5,14303 (2015).
[11] K. Yamada, D. Chiba, and T. Ono et al., Phys. Rev.
Lett. 120, 152703 (2018).

discoveries from the result is critical for making thenext connection in research. These experiences haveshown me that assumptions or a narrow prospective
pose a potential risk to losing sight of finding seeds
that may lead to breakthrough progress in future research; I learned that meaning can be understood byexperiencing something first-hand. My present motto is to enhance my professional research ability bydelving into one subject (enjoying research activity)
while having a spirit to challenge what is regarded
as impossible using common sense (simply trying). I
would like to continue to enjoy research activities byexperiencing various things and by absorbing positively what I learn.
Without great support from many people I could
have not received the Sir Martin Wood Prize. Particularly, I wish to express my deep appreciation for
the guidance and support of Professor Hideo Ohnoof Tohoku University and Professor Teruo Ono of
Kyoto University. I have come to understand various
perspectives and attitudes concerning research fromthem. I think they value the enjoyment of research
and free ideas. What I have learned in their labs isreally helpful for the present research and supervision of my lab in The University of Tokyo.
I also would like to thank the selection committee of
the Sir Martin Wood Prize; the steering committee ofthe Millennium Science Forum; the British Embassy, Tokyo; the Embassy of Japan in UK and Oxford
Instruments KK. I think the lecture trip, including
the Sir Martin Wood Prize, is truly unique among
academic awards. I really enjoyed the trip and it wasa precious opportunity for me.

[12] Y. Hibino and D. Chiba et al., Appl. Phys. Express
10, 123201 (2017).
[13] Y. Tanaka, T. Hirai, T. Koyama, and D. Chiba at al.,Appl. Phys. Express 11, 053005 (2018).
[14] S. Ohta, A. Ando, and D. Chiba, Nature Elec. 1, 124(2018).

Reflections
I have been inspired by many researchers and could
find hints for my future research subjects from conversations and discussions with them. These hints
and interactions have often become the motivationof my research activities. In addition, I have learned
that simply trying first and picking up unexpected

Lecture Trip
University of York, University of Nottingham, University of Cambridge, University of Oxford, University College London
Contact Information
dchiba@ap.t.u-tokyo.ac.jp
20 years of the Millennium Science Forum

57

Winner in 2013

Naoya Shibata

Current title and affiliation
Professor, Institute of Engineering Innovation,
School of Engineering, The University of Tokyo

1997: B.S. Department of Materials Science, The University of Tokyo
1999: M.S. Department of Materials Science, The University of Tokyo
2003: D. Eng., Department of Materials Science, The University of Tokyo
2003-2004: Overseas Research Fellow of the Japan Society for the Promotion of Science
2004-2007: Research Associate, Institute of Engineering Innovation, The University of Tokyo
2007-2011: Assistant Professor, Institute of Engineering Innovation, The University of Tokyo
2011-2017: Associate Professor, Institute of Engineering Innovation, The University of Tokyo
2017-present: Professor, Institute of Engineering Innovation, The University of Tokyo

Development of an advanced scanning transmission electron
microscope for material science research Title and affiliation when prize awarded

Associate Professor, Institute of Engineering
Innovation ,The University of Tokyo

Abstract when prize awarded
Understanding the atomic-scale structures of surfaces and interfaces is essential to control the functional
properties of many materials and devices. Recent
advances in aberration-corrected scanning transmission electron microscopy (STEM) have made possible the direct characterisation of localised atomic
structures in materials, especially at interfaces.
In STEM, a finely focused electron probe is scanned
across the specimen and the transmitted and/or scattered electrons from a localised volume of the material are detected by the post-specimen detector(s) as afunction of raster position. By controlling the detector geometry, we gain flexibility in determining thecontrast characteristics of the STEM images and theformation mechanisms involved. Thus, it may be possible to obtain further useful information by exploringnew detector geometries in atomic-resolution STEM.
From 2006, we have been developing a segment-

ed-type STEM detector capable of atomic-resolution
imaging and proposed new imaging possibilities bycontrolling detector geometries: annular bright-field(ABF) imaging and atomic-resolution differential
phase contrast (DPC) imaging. ABF-STEM imaging
enables us to directly visualise light element atomic
columns of materials. DPC-STEM imaging can beused to detect local electric fields inside materials
and devices. We applied DPC imaging to atomic resolution STEM and succeeded in directly observing
electric field distribution inside atoms for the firsttime. This new imaging capability should assist our
fundamental understanding of the origins of properties in materials and devices.

Progress in Research
The resolution of electron microscopes continues tobe improved year by year because of rapid progressin the development of aberration correction lensFig.1:Experimental atomic electric field imaging of a BaTiO3 single crystal using atomic-resolutiondifferential phase contrast STEM.

58

20 years of the Millennium Science Forumsystems. In 2017, our group in The University ofTokyo and JEOL Ltd. (a world leader in electron microscopes) attained world record spatial resolutionof 40.5 pm through state-of-the-art aberration-corrected STEM. 40.5 pm is even smaller than the Bohrradius, which means that we can make an electronprobe smaller than the size of a single atom. Usingsuch a small probe, it is now possible routinely to
directly visualise atoms inside materials and devices.
However, my current interest is whether we can go
beyond simply seeing atoms.
When I received the 15th Sir Martin Wood Prize, in
2013, I started trying to observe the electric field at
atomic dimensions using DPC STEM with a highspeed segmented detector. After several years, wecame to the stage that we could map out more precisely and quantitatively the electric field distribution
inside atomic columns in crystals and even inside
single atoms. The Figure shows a normal atomic-resolution STEM image and a two-dimensional
electric field vector map of SrTiO3 crystal observed
simultaneously. The colour contrast corresponds to
the relative direction and strength of the electric fieldat each raster position in the image. Compared withthe simultaneous normal atom image, disks of rotating colour contrast are seen at each atomic column
position in the electric field image. The directionof rotating colour contrast points outward from thecentre of the atomic columns. This is because we areobserving the electric field between the positively
charged atomic nucleus and the negatively charged
electron cloud that surrounds it. Thus, by combining the highest resolution STEM and the developed
DPC imaging technique, we are now directly observing inside the structure of atoms in real-space!
This atomic electric field should possess information
about the atomic species, local chemical bonding
and charge redistributions in between bonded atoms,
so our next challenge will be to directly visualiseelectron distribution in between atoms, i.e. bonding.
Also, we are developing a novel atomic-resolution
electron microscope that realises a magnetic field
free environment at a sample position. This new microscope will be useful for studying atomic scale
phenomena of magnetic materials and devices.
Direct magnetic structure imaging at atomic
resolution will be my next big challenge, too.

Fig.2:Normal atomic-resolution STEM image (left) and two-dimensional electric field vector map (right) of SrTiO3 crystal observed along [001] direction [Nature Comm. (2017)].

ReflectionsFirst, I would like to congratulate the Sir Martin
Wood Prize on its 20th anniversary. It was my greatest honour and pleasure to be awarded the 15th Sir
Martin Wood Prize. Indeed, my research direction
and career has been largely influenced by this prize,
in a very good way.
My lecture tour to the UK, in particular, was a great
opportunity for me to think deeply about my past,current and future research directions. I remember
vividly the wonderful time I had while visiting five
famous universities in the UK. I met many scientists
and students and had very stimulating and exciting
discussions. Of course, I also enjoyed the beautiful
scenery, history, culture, food (and beer!) of the UK.
It was an unforgettable experience to visit Sir Martin
Wood and his wife Audrey at their home. Sir Martin
kindly showed me The Manor House, which wasvery impressive, as well as some places that played
a role in the history of Oxford Instruments. I think
this lecture tour makes the Sir Martin Wood Prizevery different from others; it is outstanding. I really
hope the Millennium Science Forum and Oxford Instruments will continue this very important activity
to encourage and stimulate many young scientists
in Japan, the UK and even worldwide. I also hope
many ambitious, talented young researchers will be
continuously turned out through this great prize.
Lecture Trip
University of Glasgow, University of Manchester,
University of York, University of Oxford, Universityof Cambridge, Daresbury Laboratory
Contact Information
shibata@sigma.t.u-tokyo.ac.jp
20 years of the Millennium Science Forum

59

Winner in 2014

Masamitsu Hayashi

Current title and affiliation
Associate Professor, Department of Physics, The
University of Tokyo & Group leader, Spin Physics
Group, National Institute for Materials Science

2000: B.S., Applied Physics, Tohoku University
2002: M.S., Applied Physics, Tohoku University
2007: Ph.D, Stanford University, Materials Science and Engineering
2007-2008: Post-doctoral fellow, IBM Almaden
2008-present: Senior research scientist, National Institute for Materials Science
2016-present: Associate Professor, Department of Physics, The University of Tokyo

Effective field measurements and spin torque dynamics
in magnetic nanostructures
Title and affiliation when prize awarded

Senior research scientist, National Institutefor Materials Science

Abstract when prize awarded
The control of electrons spin orientation in solids isthe holy grail of Spintronics research. A particular focus has been placed on manipulating the electrons’
spin orientation by electrical means, that is, to control the magnetization direction of ferromagnets bypassing current or applying electric field to the system. The "spin transfer torque" allows such electrical control of magnetization: a spin polarized current
generated by passing current into a ferromagnetic
layer can be supplied to another ferromagnetic layer
to switch its magnetization direction.
We have studied the current induced motion ofmagnetic domain walls in magnetic nanowires.
Magnetic domain walls are boundaries that separate
regions magnetized in different directions. The motivation of this study is to build the Racetrack Memory proposed my supervisor Dr. Stuart Parkin. Usingnanosecond current pulses, we demonstrated in-sync
motion of multiple domain walls. The direction towhich the domain walls moved was against the current flow, consistent with the theory of spin transfer
torque. This work was press released by IBM andwas published in the journal of Science in 2008.
The use of spin polarized current to manipulatemagnetization triggered efforts to develop means ofmagnetization control in a more efficient way. Of
particular interest was the use of "spin current". Spincurrent consists of electrons possessing opposite
spins moving in opposite direction and is considered
to provide technologically viable approaches to controlling magnetization.
60

20 years of the Millennium Science ForumKey to the generation of spin current is the strong
spin orbit interaction of the material. Using a heterostructure that consists of a paramagnetic metal layer
with strong spin orbit interaction and a few atomic
layer thick ferromagnetic layer, we have studied thecurrent induced effects on the magnetization. Spincurrent generated from the paramagnetic layer via
the "spin Hall effect" exerts torque on the magnetization of the ferromagnetic layer, causing magnetization switching and motion of domain walls.
Using unique transport measurements, we revealed
the unique characteristics of the torque that occur at
the paramagnetic/ferromagnetic layer interface. In
addition, we find that the chirality of the magnetic
order of such system can be controlled by materials
engineering of the bilayer system owing to the interfacial anti-symmetric exchange interaction known as
the Dzyaloshinskii-Moriya interaction. These works
were published in Nature Materials and Nature
Communications in 2013, 2014.

Progress in Research
Three years have passed since I received the Sir
Martin Wood Prize and significant advances are
made in many areas of the field. The combinationof spin current generation from the spin Hall effectand the chiral magnetic order via the Dzyaloshinskii-Moriya interaction has led to findings of heterostructures that enable fast motion of domain walls
and is being applied for the Racetrack memory technology. On a similar line, the chiral magnetic order
is now utilized to generate skyrmions, a topologicalobject that can also be used to construct Racetrack
memory. Current induced motion of skyrmions has
been observed and various approaches to controlling
the topological object have been proposed and are
now being experimentally verified. On the front ofgenerating spin current or local spin density known
as "spin accumulation", interest has been shiftedfrom the elements in the periodic table to alloys andmultilayers. Of particular interests are the topological insulators, whose surfaces allow generation of
giant spin accumulation. Indeed, recent reports haveshown that the current density needed to control themagnetization of an adjacent magnetic layer canbe orders of magnitude smaller when topologicalinsulators are used instead of the conventional paramagnetic heavy metal. Although the mechanism of
how spin current/spin accumulation is created at theinterface is under debate, the uniqueness of the electronic state of topological insulators may continue tostimulate research for the coming years.
We have been working on various material systems
and approaches to control the spin orbit interaction ofthin film heterostructures and explore the fascinating
physics that may arise. The large spin current generated from the large spin orbit coupling of the material can in turn influence its resistivity. Such effect,
known as the spin Hall magnetoresistance, provides
means to characterize the size of spin current generated from the spin Hall effect and others. We haveused this approach to study the spin Hall effect of
the early 5d transition metals (with near amorphous
structure) and found the conductivity of the spincurrent generated via the spin Hall effect depends
on the number of 5d electrons. These results suggestthat the spin Hall effect of the early 5d transition
metals originates from the unique band structure ofeach element, which is known as the intrinsic contribution to the spin Hall effect. Applying the conceptof spin Hall magnetoresistance, we have succeededin observing the direct conversion of heat current
to spin current, often referred to as the spin Nernst
effect, in tungsten. We find that the efficiency of heatto spin conversion is similar to that of current to spin
conversion.
More recently, we have been working on theforefront of photon-spin coupling, where we use
circularly and/or linearly polarized light to probe
and control the electrons’ spin orientation. As thephoton/spin interface can be applied to quantum information technologies, solid understanding on the
coupling between the two is needed which we hopeto provide in the near future.

Reflections
Congratulations to the Sir Martin Wood Prize forits 20th anniversary! It is simply a great honour tobe awarded this prize as a scientist in the field ofcondensed matter physics. Personally, I would liketo thank the Millennium Science Forum and Oxford
Instruments for their support and providing me an
opportunity to meet many people around the world.
I am also very grateful to Sir Martin and Audrey
Wood for their hospitality and their time for showing me the history of superconducting magnets andOxford Instruments. Perhaps the uniqueness of thisaward is also due to the selection committee who,
I heard, vigorously discuss the nominees’ researcheach year to decide the awardee.
My visit to Stuttgart and the UK was an exceptional event that I will remember till I lay in my grave.
I thank Professor Takagi for inviting me to the MPI
at Stuttgart: I vividly remember the discussions (notparticularly related to science) we had in his office.
It was inspiring to travel around and see the historyof Oxford and other cities in the UK. The muscle
men winding the superconducting wires around atiny bobbin at Oxford Instruments was one of thehighlights of the trip. But without Tony Ford and Dr.
Dinah Parker, I would have been lost somewhere in
the middle and I would like to thank their support
throughout my trip.

Lecture Trip
Max Planck Institutes Stuttgart, University of Oxford, Imperial College London, University of Cambridge, University of York
Contact Information
mhayashi@qspin.phys.s.u-tokyo.ac.jp
20 years of the Millennium Science Forum

61

Winner in 2015

Takuya SatohCurrent title and affiliation
Associate Professor, Department of Physics,
Faculty of Science, Kyushu University

1998: B.Eng. Department of Applied Physics, The University of Tokyo
2000: M.Eng. Department of Applied Physics, The University of Tokyo
2004: Ph.D. Department of Applied Physics, The University of Tokyo
2003-2005: Research Fellow, Max Born Institute, Germany
2006-2007: JST Research Fellow, The University of Tokyo
2007-2014: Assistant Professor, Institute of Industrial Science, The University of Tokyo
2010-2014: JST-PRESTO Researcher
2014-Present: Associate Professor, Department of Physics, Kyushu University

Generation and control of magnetic excitations by polarized
light in antiferromagnets and ferrimagnets Title and affiliation when prize awarded

Associate Professor, Department of Physics,
Faculty of Science, Kyushu University

Abstract when prize awarded
The interaction between light and magnetism is considered a promising route to the development of energy-efficient data storage technologies. The Faraday
effect is a well-known magneto-optical effect. Linearly polarised light passing in the direction parallelto the magnetisation is subject to Faraday rotation.
In this effect, we can say that magnetism acts onlight. There is also an inverse effect; namely, wherelight acts on magnetism. The inverse Faraday effectis where circularly polarised light generates an effective magnetic field. Conversely, linearly polarised
light passing in the direction perpendicular to themagnetisation is subject to magnetic birefringence.
This is called the Cotton-Mouton effect, which is asecond-order magneto-optical effect. The inverse
Cotton-Mouton effect is where linearly polarized
light generates an effective magnetic field. These
inverse magneto-optical effects have been used for
non-thermal optical excitation of spin oscillations in(weak)ferromagnets.
The resonance frequency of spin oscillation in antiferromagnets is extremely high due to the exchangeinteraction between adjacent spins, and faster magnetisation control had been expected. However, it
was believed that the inverse Faraday effect does not
act on pure antiferromagnets with zero net magnetisation. Optical control of antiferromagnets had notbeen reported. We succeeded in excitation of spin
oscillation in NiO by illuminating circularly polarised light pulses and in optical control of antiferromagnets.
62

20 years of the Millennium Science ForumWe also demonstrated, for the first time, time andphase resolved imaging of spin wave propagation ina ferrimagnet induced via the inverse Faraday effect.
It was shown that the wave number distribution of
the excited spin wave is proportional to the frequency component of spatial spot of the excitation beam.
This fact led to the directional control of spin wave
propagation, thus demonstrating spin wave manipulation by using spatially shaped optical pulses.
Finally, we have demonstrated the one-to-one transfer of the polarisation eigenstates of a fully polarised
pump light wave onto the magnetic eigenmodes of athree-sublattice antiferromagnet. We converted themagnetic information back into the optical polarisation eigenstate of a probe light wave in an equally
one-to-one process.
These results will pave the way for new fields of“terahertz-spintronics” and “optomagnonics” forgenerating and controlling magnetic excitations bypolarised light.

Fig.1:Schematic for propagation of spin waves excited by femtosecond laser pulses.

Progress in Research
Terahertz spintronics
Antiferromagnetic materials are nowadays studied
more extensively in view of terahertz magnetisation
control using femtosecond laser pulses as well as
terahertz magnetic field pulses. Nonlinear excitationof magnetization leading to magnon-magnon andmagnon-phonon interactions, and its relaxation areimportant subjects. Furthermore, coherent and ultrafast spin manipulation/magnetization reversal withshaped pulses will be investigated.
Optomagnonics
In our technique, neither microwaves nor spin-polarized current are used at all; the spin wave isgenerated and directed only by the spatially shaped
light pulse. We expect that our technique will allow
much higher design flexibility in magnonics, andthat this technique will pave the way for a new fieldof "optomagnonics" for manipulating spin waves
with light spots of various shapes. We will work on
spatial light modulation using computer generated
holograms toward arbitrary tuning of the spin wave
propagation.

Kurosawa for arranging everything as a secretariat.
And finally, I would like to give special thanks to
Tony Ford for his tremendous effort in arranging
the lecture tour. During the time I spent with Tony, I
learnt about the British culture from him.

Fig.2: Two-dimensional maps of spin-wave emission.

Reflections
Hearty congratulations for the 20th anniversary of
the Sir Martin Wood Prize. I feel very honored to be
one of the recipients of the Sir Martin Wood Prize. It
is surely a great opportunity and a gift of encouragement to my career.
The lecture tour was truly exceptional, it was reallya once-in-a-lifetime experience for me. The experience will be appreciated in my mind for a long time.
I still keep in touch with people who I met on thetour, and will develop future relationships between
the UK, Germany, and Japan.
I sincerely thank Sir Martin Wood, Professor Noboru Miura, Professor Maki Kawai, Mr. Kitaura, Mr.
Watanabe, Sir Peter Williams and all the steeringcommittee members of the Millennium Science
Forum, Professor Hidetoshi Fukuyama, Professor
Hidenori Takagi and all the Prize Selection Committee members, the British Embassy in Japan, Japanese
embassy in the UK, and people from Oxford Instruments in Japan and the UK. I am grateful to Hidemi

Fig.3: Lecture at the University of York

Lecture Trip
Max Planck Institutes Stuttgart, University of Oxford, University of Exeter, University of York
Contact Information
satoh@phys.kyushu-u.ac.jp
20 years of the Millennium Science Forum

63

Winner in 2016

Akihito Ishizaki

Current title and affiliation Professor,
Institute for Molecular Science, National Institutes of Natural Sciences

2001: B.S., Faculty of Science, Kyoto University
2008: D.Sc., Department of Chemistry, Kyoto University
2008-2010: Japan Society for the Promotion of Science Postdoctoral Fellow for Research Abroad,
University of California, Berkeley (USA)
2010-2012: Postdoctoral fellow, Lawrence Berkeley National Laboratory (USA)
2012-2016: Research Associate Professor, Institute for Molecular Science
2016-present: Professor, Institute for Molecular Science
2016-present: Professor, School of Physical Sciences, Graduate University for Advanced Studies

Theory of real-time quantum dissipative dynamics and its
application to photosynthetic light harvesting systems
Title and affiliation when prize awarded
Professor, Institute for Molecular Science

Abstract when prize awarded
Essentially, a quantum system never can be regarded as an isolated system. Quantum systems arealways in contact with “the outside world.” Hence
their quantum natures are sometimes sustained andsometimes destroyed. In condensed phase molecularsystems, especially, quantum systems are affected bya huge number of dynamic degrees of freedom, suchas solvent molecules, amino acid residues in proteins, and so forth. Balance between robustness andfragility of the quantum natures may dramaticallyalter behaviours of chemical and biophysical dynamics. On the experimental side, it has become possible to explore molecular processes on a timescale
down to femtoseconds by means of ultrashort laser
pulses. This progress in spectroscopy has opened up
real-time observation of dynamic processes in complex molecular systems and has provided a strong
impetus to theoretical studies of real-time quantum
dissipative dynamics.
Investigation on the primary steps of photosynthesis
is an example of such efforts. Photosynthetic energy
conversion starts with the absorption of a photon ofsunlight by one of the light-harvesting pigments, followed by the transfer of electronic excitation energy
to the reaction centre. Ultrashort timescales of photosynthetic energy transfer require that all the relevant timescales in the problem be self-consistently
included in any physical model that attempts to elucidate the mechanisms. Ordinarily, photosyntheticenergy transfer is discussed in terms of the mutual
relation between magnitudes of reorganisation en64

20 years of the Millennium Science Forumergy characterising pigment-protein coupling andexcitonic coupling between pigments. In our work,
however, the main stress fell on the fact that the nature of the energy transfer is also dominated by themutual relation between two timescales, the protein
reorganisation time and the inverse of the excitonic
coupling. Considerations about the finite timescaleeffects of protein-induced fluctuation-dissipation
led to the rigorous theoretical framework describing
photosynthetic energy transfer. As a consequence,
we revealed that the photosynthetic energy transfer
process is well-optimised in the parameter region
corresponding to nature by utilising a fine balance
between the quantum mechanical delocalising effect and the protein-induced localising effect of theelectronic excitations. A series of our papers was
not only well accepted in the community of photosynthetic research, but also stimulated a burst ofactivity among multidisciplinary communities, suchas condensed phase chemical physics and quantum
physics.

Progress in Research
By taking advantage of insights and theoretical techniques obtained from photosynthetic research, wehave been investigating artificial systems such asorganic photovoltaic systems. Organic photovoltaic
systems consist of a blend of donor and acceptor
organic materials, and the photogenerated molecular exciton in the donor domain would dissociate at
the donor/acceptor heterojunction into a hole andelectron. Subsequently, the electron and hole would

separate into free charge carriers to be extracted as
photocurrents. In efficient organic photovoltaic materials, the electron and hole escape from the heterojunction and long-range charge separation proceeds
efficiently.
However, a question naturally arises concerning
the physical mechanism of the long-range charge
separation process. This is because the electron andhole are subject to their mutual Coulomb attraction,
hence they might be thought to relax to a boundelectron-hole pair localised at the interface. The recombination of the once-separated electron and holeis a major loss mechanism in photovoltaic systems
that control their performance. Hence, it is the key toelucidate physical mechanisms of how the electron
and hole escape from the donor/acceptor interface
for understanding the crucial factors determining theenergy conversion efficiency of organic solar cells.
Furthermore, from the standpoint of fundamental
physics, it can be said that great strides in the development of organic solar cells have posed fundamental physical problems regarding quantum dynamical
phenomena related to exciton and charge generationand transport in complex molecular systems.
Recently, we theoretically proposed a “non-Markovian quantum-classical ratchet mechanism” madepossible via the combination of quantum delocalisation and its decoherence, to get insight into theinner working of experimentally observed ultrafast
long-range charge separation and protection against
the charge recombination at the donor/acceptor interface. Our theoretical and computational results
revealed the following steps enabling the ratchetmechanism: (1) The electron travels using quantum delocalisation, straddling multiple molecules,
leading to the fast and long-range forward electrontransfer. (2) Subsequently, the small polaron formation induces decoherence to localise the productstate. This time-lagged decoherence is crucial because the quantum delocalisation would allow facile
backward transfer away from the product state. (3)Then, the backward electron transfer is suppressed
because it requires incoherent hopping that needs toovercome free energy barriers. Specifically, it was
revealed that the non-Markovian effect—originatedfrom slow timescales of the polaron formation—strongly suppresses the electron transfer reaction to
the interfacial charge transfer state stabilised at thedonor/accepter interface and plays a critical role formaintaining the long-range electron-hole separation.

Reflections
I would like to express my sincere gratitude andcongratulations on the 20th anniversary of the Sir
Martin Wood Prize. Although I was awarded the18th Sir Martin Wood Prize, it is my great honor
to be the 20th awardee. Last year, I had invaluable
experiences on the Sir Martin Wood Prize lecture
tour in Germany and the UK; it is still as fresh in mymind as if it had happened yesterday. In particular,
I feel a great sense of gratitude to Sir Martin Woodand his wife, Audrey, as well as Professor Hidenori
Takagi of Max-Planck Institute Stuttgart and Dr
Michael Cuthbert of Oxford Instruments for theirheart-warming hospitality. Certainly, the invaluable
and memorable journey was impossible without
Tony Ford and Hidemi Kurosawa, who made extensive arrangements. I would like to express my cordial gratitude to them, too.
I was very surprised to be selected as the Sir Martin
Wood Prize winner in 2016, because my researcharea of condensed phase quantum and chemical dynamics was considerably different from those of theformer prominent awardees selected from the fieldof condensed matter physics. I am grateful for thebroadness of themes covered by the Sir Martin Wood
Prize. I believe it represents the open-mindedness ofthe selection and steering committees in accepting
heterogenous material. I believe this open-mindedprize will continue to stimulate younger researchersof condensed matter science and to encourage further growth of the research fields.

Lecture Trip
Max Planck Institute Stuttgart, University of Oxford, University College London, University ofManchester, University of Leeds
Contact Information
ishizaki@ims.ac.jp
20 years of the Millennium Science Forum

65

Winner in 2017

Michihisa Yamamoto

Current title and affiliation
Associate Professor Quantum-Phase Electronic
Center, The University of Tokyo, Unit Leader,
RIKEN Center of Emergent Matters, RIKEN

Michihisa Yamamoto was born in Shizuoka prefecture, Japan in 1976. He received his B. Sc. (1999),
M. Sc. (2001), and Ph.D. (2004) in physics from the University of Tokyo. He was a research Associate Professor (2004-2014) and a lecturer (2014-2017) in the Department of Applied Physics and an
Associate Professor (2017-2018) in Quantum-Phase Electronics Center at the University of Tokyo.
Since 2017, he is a unit leader at RIKEN Center for Emergent Matter Science.

Measurement and control of the phase of an electron wave
Title and affiliation when prize awarded
Associate Professor Quantum-Phase Electronic
Center, The University of Tokyo

Abstract when prize awarded
The phase of a wave function is the most fundamental concept of quantum mechanics. Among avariety of interference phenomena that can reveal
this quantum phase, a two-path interference is thesimplest. Consequently, the Aharonov-Bohm (AB)interferometer, which is usually considered as a twopath interferometer, has been the most popular playground for physicists. In the AB interferometer, therelative transmission phase between the two paths
can be controlled by external magnetic field B. This
phase difference causes an oscillation of the current
as a function of B. It turned out, however, that the
two-terminal linear conductance through an AB ring
suffers from the so-called phase rigidity.
Onsager’s law for linear conductance, G(B)=G(-B),
implies that the phase of the AB oscillation can only
take the values 0 or π at B = 0. To satisfy this boundary condition, contribution from paths of an electron
encircling the AB ring multiple times needs to be
added. What is usually observed in an AB experiment is therefore not an ideal two-path interference.
Using multi-terminal as well as multi-channel ABinterferometers, numerous attempts have been madeto measure and control the phase shift of an electron
wave, however, no reliable phase measurement had
been realised.
In this work, we showed that a pure two-path interference is realised by combining the AB ring withparallel tunnel-coupled quantum wires that allow
66

20 years of the Millennium Science Forumtunnelling of an electron between the two paths.
Adjusting the tunnel coupling energy, we can monitor and suppress the contribution of encircling paths
while keeping the large AB oscillation amplitude.
This solid-state analogue of the double-slit experiment allows for measurement and control of the truetransmission phase shift of an electron.
We applied this phase measurement technique toinvestigate the scattering of an electron wave by an
artificial atom. We embedded a quantum dot into
one of the two paths of the interferometer to measure the scattering phase through an artificial atom. In
addition to the Friedel sum rule, which connects thenumber of electrons in the quantum dot to the scattering phase, we have revealed influences of the parity of orbital wave function and the interaction between a local spin confined in the quantum dot andconducting electrons in the reservoirs, i.e. the Kondo
effect. In particular, we observed π/2 phase shift in
the Kondo regime as the hallmark of the Kondo effect, interpreted as the fingerprint of local moment
screening.

Progress in Research
I am extending the concept of “quantum electron
wave technology” (citation of the award). I plan touse a special kind of quasi-particles, which are defined as elementary excitation of correlated statesthat can travel over macroscopic distance without
suffering from decoherence, as information carriers
on quantum electron waves. In addition, I am trying

to use “standing waves” to detect finite size effectsof quantum systems. My recent research involves
using two-dimensional layer materials such asgraphene and transition metal dichalcogenide. I am
also starting up a new laboratory in RIKEN.

Reflections
I felt extremely honoured when I was awarded the
Sir Martin Wood Prize. Honestly speaking, it wasmore than I expected. I appreciate very much thatthe selection committee evaluated highly my workon the measurement and control of the phase of anelectron wave. For the purpose of young researchers,
in particular, I would like to describe how I could
achieve it.
Measurement and control of the phase is a very
well-known, long-term and fundamental problem.
I believe that, about 20 years ago, most researchers who had nanofabrication and low temperature
measurement facilities were making some attempts
at it. Despite a lot of efforts by many people, nobody
could do it, although some researchers claimed thatthey could. Their results were inconsistent with theories, even at very fundamental stages.
On the other hand, efforts made in these previous
works were indeed significant. Some employed very
complicated device structures as well as the mostadvanced measurement skills. Researchers therefore
claimed that they did the best imagined in the world
and that inconsistency with theories indicates thatthose theories overlook something.
With such a message delivered to the community,
many people were misled that the problem was atleast experimentally solved. This was the situation
when I conceived and started this project. I had tostart by convincing people in my own group that the
problem had not at all been solved experimentally. Once I obtained promising data, my supervisor,
Professor Seigo Tarucha gave me significant support and encouragement. Then the number of people involved increased; I was joined by Dr Shintaro
Takada and Dr Christopher Bäuerle, without whom
I believe I could never have gained such a great
achievement. All those involved really liked the project and became highly motivated and excited.
But there were also some risks. First, the work was
not so easy, particularly in the beginning, due to thenumber of misled people; we sometimes got aggressively negative referee comments when we submitted papers. Also, as the theoretical work has largely
been established and our experiments were quite
conclusive, we could not expect a good “citation
number” in the short-term.
Apart from our absolute confidence in what we were
doing, our motivation was that we wanted simply toknow the truth and see the view from the top in thisfundamental issue; we expected to see and open up
something very new and fundamental. I believe that
this kind of motivation is more important than hoping to get a good reputation by simply following ashort-term trend.

Lecture Trip
Max Planck Institute Stuttgart, University of Cambridge, University of Oxford, University of Manchester, University College, London
Contact Information
michihisa.yamamoto@riken.jp
20 years of the Millennium Science Forum

67

Winner in 2018

Yoshihiko Okamoto

Current title and affiliation
Associate Professor, Department of Applied
Physics, Nagoya University

2001: B.S. Department of Applied Chemistry, The University of Tokyo
2003: M.S. Department of Advanced Materials Science, The University of Tokyo
2006: Ph.D. Department of Advanced Materials Science, The University of Tokyo
2006: Special Postdoctoral Researcher, RIKEN
2006-2014: Research Associate, Institute for Solid State Physics, The University of Tokyo
2014-present: Associate Professor, Department of Applied Physics, Nagoya University
2014-2018: Associate Professor, Institute for Advanced Research, Nagoya University

Exploration of Novel Physical Properties and Functions of Transition
Metal Compounds Based on the Unique Electronic and Crystal Structures

Abstract when prize awarded
Novel transition metal compounds with remarkable electronic properties, such as cuprate and ironbased superconductors, have opened up a new eraof the condensed matter physics. In my Sir Martin
Wood Prize lecture I will present the results ofmaterial exploration of transition metal compounds
using the crystal and electronic structure databases
based on knowledge of solid state chemistry, toward the discovery of such electronic properties andfunctions. We developed various materials including
high-performance thermoelectric materials, candidate nodal-line semimetals, metal-insulator transition systems, superconductors, and geometricallyfrustrated magnets and I will focus on the former
two systems.
1. One-dimensional telluride Ta4SiTe4 as a highperformance thermoelectric material.
Thermoelectric cooling is a promising candidate
for the next-generation of refrigeration technologies
in replacing vapor compression cooling using gaseous refrigerants. However, there is currently no bulk
material with a high enough performance to reacha practical level in the low temperature region. We
found that Ta4SiTe4 and its substituted compounds
show high thermoelectric performance at low temperature. Thermoelectric power of Ta4SiTe4 whisker
crystals reaches S = -400 μV K-1 at 100-200 K, while
maintaining low resistivity of ρ ~ 2 mΩ cm. These S
and ρ give a larger power factor of P = S2/ρ of 80 μW
cm-1 K-2 than those in Bi2Te3-based practical materials
68

20 years of the Millennium Science Forumat room temperature, indicating that Ta4SiTe4 is apromising candidate for the low temperature applications of thermoelectric cooling. This very large P
is probably caused by the very small spin-orbit gap
opening on the strongly one-dimensional electronic
bands at the Fermi energy.
2. CaAgP and CaAgAs as a candidate nodal-line
semimetal.
In recent years, Dirac and Weyl semimetals, whichare zero-gap semiconductors with linear dispersion
bands at the zero-gap points, have attracted broadinterest as candidate systems for realizing topologically nontrivial states in bulk materials. In contrast,some systems are theoretically indicated to have anodal line, where the linear dispersion bands crosson a line in the momentum space. We found that
CaAgP and CaAgAs are promising candidates forthe nodal-line semimetal. First principles calculation
results indicate that the both compounds are ideal
nodal-line semimetals, where the Dirac points forma ring at the Fermi energy. We synthesized polycrystalline samples and single crystals of CaAgP and
CaAgAs and found that they have a ring-torus Fermi
surface related to the nodal ring by physical property
measurements of them.

Reflections
It is great honor for me to receive the Sir Martin
Wood Prize. I have been exploring novel transition
metal compounds since I was a graduate student. I
was thinking how I can contribute to the progress ofcondensed matter physics, although I have a background of chemistry. I can neither develop a theory
by using complex mathematical formulae nor conduct sophisticated physical property experiments
based on the latest finding in physics. However, I
could find various interesting materials and makethem visible to physicists by using my knowledgeof solid state chemistry. I was unsure whether thismethod has scientific significance, but this award
gives me confidence and I’m grateful to committee members of the Millennium Science Forumand Sir Martin Wood Prize selection committee forrecognizing my work. Another great thing about amaterial exploration study is that one can directly
collaborate with many experimentalists and theorists
through the novel materials. My study is supported
by many of these collaborators. I would like to thankmany people including the collaborators, my supervisors, staff of our department, and present and pastmembers of our research group.
Contact Information
yokamoto@nuap.nagoya-u.ac.jp

Prize Selection Committee Meeting
The Nomination period for the 2018 Sir Martin Wood Prize was from 1st April to 1st August 2018.
The prize selection committee met on 2nd September 2018 (below) and chose Dr. Yoshihiko Yamamotoas the winner.

20 years of the Millennium Science Forum69

Sir Martin Wood Prize Winners 1999 – 2018
In alphabetical order

Family nameFirst nameAwardedyear

Current title and affiliation

Chiba

Daichi2012

Associate Professor, Department of Applied Physics, The University ofTokyo

Fujisawa

Toshimasa

2003

Professor, Department of Physics, Tokyo Institute of Technology

Hayashi

Masamitsu

2014

IshizakiAkihito2016

Kawano

Yukio

2011

KimuraTsuyoshi

2005

Kim

Yousoo2009

Associate Professor, Department of Physics, The University of Tokyo &Group leader, Spin Physics Group, National Institute for Materials Science
Professor, Institute for Molecular Science, National Institutes of Natural
Sciences
Associate Professor, Laboratory for Future Interdisciplinary Research of
Science and Technology, Tokyo Institute of Technology
Professor, Graduate School of Frontier Sciences, The University of Tokyo
Chief Scientist, Director of Surface and Interface Science Laboratory,
RIKEN

KizukaTokushi

2000

Professor, Department of Materials Science, University of Tsukuba

Murakami

Shuichi2010

Nakamura

Yasunobu

1999

Professor, Department of Physics, Tokyo Institute of Technology PRESTO, Japan Science and Technology Agency
Professor, Research Center for Advanced Science and Technology, The University of Tokyo, Team Leader, Center for Emergent Matter Science, RIKEN

Ohno

Yuzo

2004

Professor, Faculty of Pure and Applied Sciences, University of Tsukuba

Ohtomo

Akira

2007

Professor, Department of Chemical Science and Engineering, Tokyo Institute of Technology

OkamotoYoshihiko

2018

Associate Professor, Department of Applied Physics, Nagoya University

Ono

Teruo

2008

Professor, Institute for Chemical Research, Kyoto University

Satoh

Takuya2015

Associate Professor, Department of Physics, Faculty of Science, Kyushu University

SaitohEiji

2008

Professor, Department of Applied Physics, The University of Tokyo

Shibata

Naoya

2013

Shimizu

Katsuya

2000

Professor, Institute of Engineering Innovation, School of Engineering,
The University of Tokyo
Professor, Division of Materials Physics, Graduate School of Engineering Science, Osaka University

Shirahama

Keiya

2001

Professor, Department of Physics, Keio University

Suenaga

Kazutomo

2006

Prime senior researcher : National Institute of Advanced Industrial Science and Technologies

TerasakiIchiro2002

Professor, Department of Physics, Nagoya University

Yamamoto

Michihisa

2017

Associate Professor Quantum-Phase Electronic Center, The Universityof Tokyo, Unit Leader, RIKEN Center of Emergent Matters, RIKEN

70

20 years of the Millennium Science ForumAppendix

20 years of the Millennium Science Forum71

Prize Ceremony Memories

HRH The Princess Royal awards the 1999 Millennium Science Forum Honorary Prize to Hiroshi Yasuoka

72

1999 Millennium Science Forum Honorary Prizewinner Hiroshi Yasuoka

Sir Martin awards the 1999 1st Prize to Yasunobu
Nakamura

2000 joint 2nd Prize winners Tokushi Kizuka and
Katsuya Shimizu

Sir Martin awards the 2001 3rd Prize to Keiya
Shirahama

Sir Martin awards the 2002 4th Prize to Ichiro
Terasaki2003 Guest speaker Professor Robin Nicholas,
University of Oxford

20 years of the Millennium Science ForumSir Martin awards the 2003 5th Prize toToshimasa Fujisawa

2002 Guest speaker
Professor Sir Harold Kroto, University of Sussex

Sir Martin awards the 2004 6th Prize to Yuzo Ohno

Sir Martin awards the 2005 7th Prize to Tsuyoshi
KimuraSir Martin awards the 2006 8th Prize to Kazutomo
Suenaga

Sir Graham Fry, UK Ambassador, awards the 2007
9th Prize to Akira Ohtomo

Sir Martin and Sir David Warren, UK Ambassador, award
the 2008 joint 10th Prize to Teruo Ono and Eiji Saitoh

Sir David Warren, UK Ambassador, awards the2009 11th Prize to Yousoo Kim
20 years of the Millennium Science Forum73

Prize Ceremony Memories

Sir Martin awards the 2010 12th Prize to Shuichi
Murakami

Sir David Warren, UK Ambassador, awards the2011 13th Prize to Yukio Kawano

Sir Tim Hitchens, UK Ambassador, awards the2013 15th Prize to Naoya Shibata

Julia Longbottom, UK Minister, awards the 2012
14th Prize to Daichi Chiba

2012 Guest speaker Professor
Koichi Kitazawa, President, JST

Professor Fukuyama and Professor Miura with Sir Martin Wood Prize Alumni (2012)2014 Guest speaker, Dr. Julie Maxton, Executive
Director, The Royal Society

74

20 years of the Millennium Science Forum

Sir Tim Hitchens, UK Ambassador, awards the2014 16th Prize to Masamitsu Hayashi

Sir Tim Hitchens, UK Ambassador, awards
the 2015 17th Prize to Takuya SatohSir Tim Hitchens, UK Ambassador, awards the2016 18th Prize to Akihito Ishizaki

Takuya Satoh giving the prize lecture

Paul Madden, UK Ambassador, awards the 201719th Prize to Michihisa Yamamoto

Delegates at the 2017 MSF at the courtyard of the British ambassador's residence in Tokyo
20 years of the Millennium Science Forum75

Record of the MSF
Steering Committee and Selection Committee members

76

Affiliation when appointed

MSF Committee

MSF Steering Committee

Noboru Miura

The University of Tokyo

1999-2006

2007-

Hidetoshi Fukuyama

The University of Tokyo

1999-2006

Koichi Katsumata

RIKEN

1999-2003

Koichi Kitazawa

The University of Tokyo

1999-2006

2007-2014

Yasuo Endoh

Tohoku University

1999-2006

2007-

Toshizo Fujita

Hiroshima University

1999-2003

Tomoji Kawai

Osaka University

1999-2006

2007-2009

Seigo Tarucha

The University of Tokyo

2003-2006

2007-2009

Yoshinori Tokura

The University of Tokyo

2003-2006

2007-2009

Akira Tonomura

Hitachi Ltd

Hideo Ohno

Tohoku University

2007-2017

Yoshio Kitaoka

Osaka University

2007-2014

Kazumasa Miyake

Osaka University

2007-2010

Hayao Kobayashi

IMS

2007-2009

Maki Kawai

The University of Tokyo

2008-

Yoshio Nishimura

JASTJ

2008-2015

Jiro Kitaura

Rigaku2010-

Hideaki Takayanagi

Tokyo University of Science

2010-2014

Reizo Kato

RIKEN

2010-

Hidenori Takagi

The University of Tokyo

2010-

Masashi Kawasaki

The University of Tokyo

2010-

Mariko Takahashi

The Asahi Shimbun

Naoto Nagaosa

The University of Tokyo

Robin Nicholas

University of Oxford

2013-

Sir Peter Williams

The Royal Society

2014-

Kiyoyuki Terakura

AIST

2015-2016

Hideo Hosono

Tokyo Institute of Technology

2015-

Kiyoshi Watanabe

Oxford Instruments Japan

Shinji Tsuneyuki

The University of Tokyo

2017-

Koki Takanashi

Tohoku University

2018-

20 years of the Millennium Science Forum

Sir Martin Wood Prize
Selection Committee
2007-

2007-201220112011-

2016-

Guest Speakers at the Millennium Science Forum
1st 1999 Spring
2nd 1999 Autumn
3rd 2000
4th 2001
5th 2002
6th 2003
7th 2004
8th 2005
9th 2006
10th 2007
11th 2008
12th 2009
13th 2010
14th 2011
15th 2012
16th 2013
17th 2014
18th 2015
19th 2016
20th 2017
21st 2018

The title is as was at that time.
The MSF was held twice in 1999.

Shunichi Kobayashi, President, RIKEN
Sir Peter Williams, Former Chairman, Oxford Instruments
Akito Arima, Member of the House of Councilors
Sir Martin Wood, Founder, Oxford Instruments
Leona Ezaki, President, Shibaura Institute of Technology
Mamoru Mori, Director, National Museum of Emerging Science and Innovation
Lord Robert May, Professor, University of Oxford
Jyunjiro Kanemori, Director, International Institute for Advanced Studies
Sir Harold Kroto, Professor, University of Sussex
Sumio Iijima, Professor, Meijo University
Robin Nicholas, Professor, University of Oxford
Akira Tonomura, Fellow, Hitachi Ltd.
Lord Robert May, Professor, University of Oxford
Shoji Tanaka, Director General, ISTEC Superconductivity Research Laboratory
Laurence Eaves, Professor, University of Nottingham
Maki Kawai, Professor, The University of Tokyo
Martyn Chamberlain, Professor, Durham University
Kiyoshi Kurokawa, Professor, National Graduate Institute for Policy Studies
Maurice Skolnick, Professor, University of Sheffield
Michael Brady, Professor, University of Oxford
Sukekatsu Ushioda, President, NIMS
Stephen Holloway, Professor, University of Liverpool
Hideo Hosono, Professor, Tokyo Institute of Technology
Tomas Jungwirth, Professor, University of Nottingham
Tsuneya Ando, Professor, Tokyo Institute of Technology
Anthony Cheetham, Professor, University of Cambridge
Koichi Kitazawa, President, JST
Robin Nicholas, Professor, University of Oxford
Seigo Tarucha, Professor, The University of Tokyo
Sir Peter Williams, Former Chairman, Oxford Instruments
Akira Fujishima, President, Tokyo University of Science
Dr. Julie Maxton, Executive Director, The Royal Society
Masaki Takata, Professor, Tohoku University
Kevin O’Grady, Professor, University of York
Kohzo Ito, Professor, The University of Tokyo
Chris Done, Professor, Durham University
Eleanor Campbell, Professor, University of Edinburgh
Griff Jones, First Secretary Science & Innovation, British Embassy, Tokyo
Motoko Kotani, Professor Tohoku University
Atsufumi Hirohata, Professor, University of York

20 years of the Millennium Science Forum77

20 years of the Millennium Science Forum-Attainments of Sir Martin Wood Prize Winners-

Copyright © 2018 Millennium Science Forum
Printed in Japan
Editorial Committee:
Kiyoshi Watanabe (Editor-in-Chief)
Mariko Takahashi (Deputy Editor)
Hidetoshi Fukuyama
Maki Kawai
Jiro Kitaura
Yasunobu Nakamura
Keiya Shirahama
Yousoo Kim
Yukio Kawano
Naoya Shibata
Editorial Staff:
Tony Ford
Kaori Oshima
Production Design: Career Consulting KK
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This publication is supported by Oxford Instruments KK.

The Secretariat, The Millennium Science Forum
TEL:+81-3-6732-8966
E-mail:msf@oxinst.com

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