RESEARCH HIGHLIGHTS 2011
A publication of the WPI Advanced Institute for Materials Research

RESEARCH HIGHLIGHTS 2011

WPI Advanced Institute for Materials Research
The Advanced Institute for Materials Research (AIMR) at Tohoku University in Sendai,
Japan, is one of six World Premier International (WPI) Research Centers established withthe support of the Japanese Ministry of Education, Culture, Sport, Science and Technology(MEXT). Since its inauguration in 2007, the WPI-AIMR has been bringing together worldclass researchers from Japan and abroad to carry out cutting-edge research in materials
science through interdisciplinary collaboration among its four groups: Bulk Metallic
Glasses, Materials Physics, Soft Materials, and Device/Systems, along with a newly added
Mathematics Unit.
Led by chief scientist and institute director Yoshinori Yamamoto, the center promotes
fusion research across the different groups while fostering young researchers through afusion-research proposal system and the Global Intellectual Incubation and Integration
Laboratory (GI3 Lab), where international joint research is carried out in close cooperation
with high-profile researchers invited from countries throughout the world.
The WPI-AIMR is host to over 120 leading researchers, with around half from aroundthe world, including 31 principal investigators. In addition to the research hub at Tohoku
University, the WPI-AIMR collaborates with research centers in the UK, France, Germany,
the USA and China. Close ties with other leading foreign universities are maintained
through its Adjunct Professor and Associate Professor programs.

AIMResearch
AIMResearch is an online and print publication that highlights the scientific achievements
and activities of the WPI-AIMR. First published in June 2009, AIMResearch selects themost important papers from the wealth of research produced by WPI-AIMR scientists
throughout the year, distilling the essence of the achievements into timely, concise andaccessible research highlights that are easy to digest, but retain all of the impact andimportance of the original research article. Published monthly on the AIMResearch website
in both English and Japanese, AIMResearch highlights bring the very best of WPI-AIMR
research to a global audience of specialists and nonspecialists alike. AIMResearch also
publishes a range of features articles introducing other activities of the WPI-AIMR’s researchgroups. Visitors to the website can register for monthly email alerts in either Japanese or
English to keep abreast of the latest developments and discoveries made at the WPI-AIMR.
research.wpi-aimr.tohoku.ac.jp

MESSAGE FROM THE DIRECTOR
2

A new challenge: Mathematics and materials
RESEARCH HIGHLIGHTS

in the SPOTLIGHT

6

Thin films: A tight squeeze

22

Materials research like none other

7

Energy storage: Supercapacitors with a heart of gold

24

Tearing down the walls of research

8

Metallic glasses: Local differences

26

Green innovation in the limelight

9

Magnetic memory: Less friction, lower power

27

Fusion research abounds with

10

Nanomaterials: Cool cubes for catalytic converters

11

Sustainable chemistry: Made of greener stuff

12

Spin electronics: Magnetism under control

13

Single-molecule spectroscopy: A new gold standard?

14

Superconductors: Dirac cones come in pairs

15

Superconductors: Taking charge of the future

16

Photovoltaics: Making light work of organic solar cells

17

Catalysis: A tale of two metals

18

Oxide interfaces: One atom at a time

19

Nanoclusters: Steel that breaks the rules

20

Micromirrors: Metallic glasses begin to shine

research.wpi-aimr.tohoku.ac.jp
AIMResearch is a publication of the World Premier International Advanced
Institute for Materials Research (WPI-AIMR), a Tohoku University institute fundedby the Ministry of Education, Culture, Sports, Science and Technology of Japan.
© 2011 WPI-AIMR, Tohoku University. This publication may be reproduced in its
original form for personal use only. Modification or commercial use without priorpermission from the copyright holder is prohibited.

infinite possibilities

Editorial
WPI-AIMR, Tohoku University
2-1-1 Katahira, Aoba-ku, Sendai,
Miyagi 980-8577, Japan
Editor-in-Chief

Yoshinori Yamamoto

Managing Editor

Masashi Kawasaki

Editorial AssistantMariko Onodera

ISSN 1884-491X

Message from the director

A new challenge: Mathematics and materials
As the institute director of thecreation of metallic nanoporous

catalyzing fusion research, andWorld Premier International

catalysts, which combines thewill contribute to the creation ofAdvanced Institute for Materials

fields of modern metallurgy anda new materials science. Professor

Research (WPI-AIMR), I havechemical science; and the develop-

Motoko Kotani, Deputy Director

great pleasure in welcoming you

ment of microelectromechanicaland Leader of the Mathematics

to this, the third print edition

devices based on bulk metallic

Unit, initiated the collaboration ofof AIMResearch. Last April, theglasses, in which modern metal-

mathematics and materials science

AIMResearch website entered its

lurgy is combined with device

at WPI-AIMR. The power ofthird year, and this print publica-

construction. The institute’s fusion

mathematics has a long tradition

tion is a comprehensive collection

research outcomes, coupled withof providing common languagesof the research highlights published

the accomplishments in eachto all fields of science and technol-on the website in 2011 along withresearch group, have establishedogy, and more recently it has

lively journalistic features that

WPI-AIMR as a unique world-

become a global trend for science

turn a spotlight on the people

class research institute in materials

and technology to amalgamate

and activities behind the researchscience, where various disciplines

with mathematics. Mathematics

carried out at the WPI-AIMR.

work together under one roof. Our

can simplify complicated andSince its inauguration in 2007,

recently renovated WPI-AIMR

diverse phenomena, extracting

the WPI-AIMR has consisted ofMain Building, completed in Julyfrom them the principles that canfour key research groups — Bulk

2011 and in which all four research

make it possible to predict andMetallic Glasses, Material Physics,

groups are now based, helps

create new functional material.

Soft Materials, and Device/Systems

to further enrich the institute’s

Over the next five years, the newConstruction — which haveenvironment of fusion research.

Mathematics Unit will set us on

carried out high-caliber research

The newly establisheda unique research direction thatin each discipline, as well as

Mathematics Unit, introduced

will help to further advance WPI-

dynamic fusion research between

in late 2011, will complement

AIMR as a key global research hub

disciplines. Examples of fusion

the four existing research groups

for innovation and education in

research at WPI-AIMR include theby further enhancing andnew materials science.

In this fiscal year, site-visit teams

Although Sendai, along

and the program committee of thewith WPI-AIMR and Tohoku

Japan Society for the Promotion

University, has now recovered toof Science (JSPS) undertook an

a level similar to that before theannual evaluation of WPI-AIMR,

disasters, many people living in theand an interim evaluation was

coastal region are still experiencing

conducted by the Ministry ofserious problems. The situation at

Education, Culture, Sports, Science

Fukushima is gradually improving,and Technology (MEXT). Released

but it will take a long time until theon December 14, 2011, MEXT’s

problem is completely resolved.

evaluation results encourage us to

Since March last year, people frompursue our new research direction

all over the world have supportedof mathematics–materials science

us both materially and spiritually,collaboration. I am also pleased toand I wish to extend our deepest

announce that Professor Kotani

gratitude for their generous

will lead WPI-AIMR from April

assistance. It is a pleasure for me2012 as my successor.

to say that WPI-AIMR is quickly

Finally, nearly a year has passed

recovering from the disasters, andsince the terrible triple disasters

as part of the region’s rebuildingof March 11, 2011 in which more

process, we are continuing ourthan 15, 000 people died — theresearch activities and education at

9.0-magnitude Tohoku earthquake,a faster pace than ever before.

the devastating tsunami withheights of 10 to 20 meters (in some

Yoshinori Yamamotoplaces up to 40 meters), and the

Director

subsequent crisis at the Fukushima

WPI-AIMR

nuclear power plant.

AIMResearch highlights some of the best materials research at
the World Premier International Advanced Institute for
AIMResearchhighlights
some of theTohoku
best materials
research
Materials Research(WPI-AIMR),
University,
Japan.atthe World Premier International Advanced Institute forMaterials Research (WPI-AIMR), Tohoku University, Japan.

AIMResearch introduces cutting-edge
research from the WPI-AIMR through its
concise, accessible research highlights,
AIMResearch
introduces
cutting-edge
and casts a spotlighton thescientists andresearch
from
the
WPI-AIMR
through its
laboratories of WPI-AIMR
concise, accessible research highlights,
Registermonthly on
email
to getandcastsfora spotlightthe alertsscientists
andthe latest researchnews from WPI-AIMR
laboratories
of WPI-AIMR
delivered direct to your inbox!
Register for monthly email alerts to get
the latest research news from WPI-AIMR
delivered direct to your inbox!

All articles published on AIMResearch are open access.
All articleshttp://research.wpi-aimr.tohoku.ac.jp/jpn
published on AIMResearch are open access.
http://research.wpi-aimr.tohoku.ac.jp/jpn

RESEARCH HIGHLIGHTs
The WPI-AIMR advances research in bulk metallic glasses,
materials physics, soft materials and device/systems construction, and actively promotes collaboration among these divisions
toward the development of ground-breaking technologies thatcross the boundaries of conventional fields of study — bridging
the disciplines of materials science, physics, chemistry andprecision, mechanical, electronics and information engineering.
The new Mathematics Unit, established in late 2011, will further
complement WPI-AIMR’s research activities.

Research highlights

Thin films

A tight squeeze
Insight gained into the electronic properties of lead films by combining two
characterization techniques suggests new strategies for electronic applications

6

r

cto

e
ve V
Wa

Binding Energy

Processing materials into thin films isimportant for fabricating electronic
circuits, solar cells and lasers devices.
Often only a few atomic layers thick,thin films are dominated by quantum
effects whose properties can offer
distinct performance advantages overthicker layers.
Researchers from the WPI-AIMR
in collaboration with researchers from
Tsinghua University and the Institute ofPhysics in Beijing, China, have now uncovered how such quantum effects influence the properties of thin films basedon the superconducting material lead1.
Their findings could enable new electronic applications of thin metal films.
Thin films of lead are more unusual
than those of most metals. Many of
their properties are extremely sensitive
to variations in film thickness, even by
as little as a single atomic layer. Thisbehaviour is thought to be caused byparticularly pronounced quantum effects resulting from the long distances
over which the electronic states of themetal extend, says Seigo Souma fromthe research team. “For most metals,
quantum-size effects occur at very small
thickness of less than 5 nanometers,
whereas lead films, owing to their large
electron wave length of 1 nanometers,
exhibit significant size effects even atfilm thicknesses of over 20 nanometers.”
To discover the origins of these unusual quantum properties, the researchers studied thin films of lead grownon silicon.
They combined two characterization techniques — surface scanningtunnelling spectroscopy and angleresolved photoemission spectroscopy— to correlate the relationship betweenΓ

Wave Vector

The electronic structure of lead films. The energetic states of electrons in thin films of lead are plotted as afunction of momentum and energy. Quantum effects are responsible for the shape of these electron states,with the top ring in particular being responsible for many of the observed properties.

film thickness and any exhibited
electronic features.
Charting the kinetic energy of theelectrons as a function of their momentum, the researchers discoveredthat confinement effects caused theelectronic states to form an ‘m’ shape(see image) that changes significantly
between films comprising 23 and 24
atomic layers. Of particular interest is
the circular structure that forms in the
topmost part of the structure, where avery large number of electronic states
are concentrated. The energetic positionof the ring depends on the film thickness, which in turn causes thicknessdependent oscillations in the electronic
properties of the films.

Building on this advancement in
fundamental understanding, the nextchallenge will be to investigate the superconducting properties of these thinfilms together with systems of different
geometries, such as quantum dots, wires
and stripes.
“Understanding the electronic structures of these low-dimensional systems
lies at the heart of advanced electronic
devices,” says Souma.
1. Sun, Y. J., Souma, S., Li, W. J., Sato, T., Zhu, X. G.,
Wang, G., Chen, X., Ma, X. C., Xue, Q. K., Jia, J. F.,
Takahashi, T. & Sakurai, T. Van Hove singularities
as a result of quantum confinement: The originof intriguing physical properties in Pb thinfilms. Nano Research 3, 800–806 (2010).

AIMResearch 2011

Research highlights

Energy storage

Supercapacitors with a heartof gold
Wind turbines, solar cells and other‘green’ energy technologies often encounter supply-and-demand problems
because their energy sources are intermittent. One way to overcome this is byusing supercapacitors — devices thatcan quickly store electricity by organizing positively and negatively charged
ions into two distinct electrolyte layers,
each in contact with a metal electrode.
However, while such double-layer supercapacitors are extremely robust, theenergy storage density they offer is not
sufficiently high for widespread use.
Xingyou Lang, Akihiko Hirata,
Takeshi Fujita and Mingwei Chenfrom the WPI-AIMR have been working on building supercapacitors usingtransition metal compounds such as
manganese dioxide (MnO2), which canstore charge at metal sites by an electrontransfer process called ‘pseudocapacitance’. Unfortunately, MnO2 has low
conductivity, which limits its charging
and discharging speeds. The researchers
have now shown1 that a supercapacitor
constructed using an MnO2-plated gold
film dotted with nanoscale pores has
quick-charging properties and unprecedented electrical storage capabilities.
Previous attempts to resolve theconductivity problems of MnO2 have
involved incorporating the oxide
into conductive polymers or carbon
nanotubes. Chen and his team took
a different approach by fabricating
a nanostructured MnO2–gold composite. First, they selectively etched asilver–gold alloy into a thin gold sheet
permeated with numerous nanopores.
They then grew MnO2 nanocrystals
directly into the pore channels usinga gas-phase reaction. This growth step

AIMResearch 2011

© 2011 M. Chen

Growing inorganic crystals inside nanoporous gold films boosts the speed andenergy density of charge-storing devices

50 nmTransmission electron microscopy image showing the close contact between gold (dark blue) and crystalline
MnO2 (light blue)

proved crucial to the performance ofthe supercapacitor — too much crystal
deposition would fill the nanopores
and impair the double-layer effect,
while too little crystal growth would
not provide good pseudocapacitance.
Finally, the team sealed the resulting
nanostructured electrodes and an aqueous electrolyte in plastic, creating a thinand flexible supercapacitor.
The device displayed excellent chargestorage capacity with an energy density
up to 20 times higher than that of other
MnO2 electrodes. The supercapacitor
also displayed near-ideal high-speed
charging behavior, which high-resolution microscopy revealed to be due
to intimate contact between the MnO2
crystals and the conductive gold surface(see image). “We did not expect theformation of such a good interface because of the obvious differences in lattices and chemical properties between
gold and MnO2,” says Chen.
These properties, in combination
with fast ion diffusion through thethree-dimensional nanoporous structure, result in an enhanced supercapacitor with promising applications.
Chen and his team are currently investigating how to utilize the MnO2–gold
composite for electrodes in lithium-ion
batteries, and are attempting to develop
other mixed nanoporous materials witheven higher energy densities.
1. Lang, X., Hirata, A., Fujita, T. & Chen, M.
Nanoporous metal/oxide hybrid electrodes
for electrochemical supercapacitors. Nature
Nanotechnology 6, 232–236 (2011).

7

Research highlights

Metallic glasses

Local differences

Most metals are crystalline in structure,with their constituent atoms arranged ina regular pattern. Amorphous or glasslike metals, on the other hand, have little
or no atomic ordering, and thus haveseveral advantages over crystalline metals. For example, they can be easily softened and shaped, and are often stronger
and more deformable than a crystalline
metal with the same composition.
Metallic glasses are formed by coolinga hot metallic melt fast enough to prevent its atoms from rearranging to forma crystal. They are highly conductive, likeregular metals, but also exhibit enhanced
strength and viscoelasticity. Althoughmetallic glasses have been studied for
decades, the initial idea that their properties are homogeneous has recently
shifted towards heterogeneity at thenanoscale. Now, Mingwei Chen, Yanhui
Liu and colleagues at the WPI-AIMR
and the Institute for Materials Researchat Tohoku University have characterized the nanoscale elastic properties ofmetallic glasses1.
The researchers used radiofrequency
magnetron sputtering to form an atomically flat, 2 μm-thick film composed ofthe metals zirconium, copper, nickel andaluminum, and also showed the film tohave a glassy structure.
The researchers then studied its surface using a technique previously developed by Ken Nakajima and Toshio Nishi— members of the research team — forpolymeric materials, but they found that
it was also suitable for metallic glasses.
The technique involves moving a vibrating cantilever with a sharp tip, whose
apex is just 1 nanometer in radius, acrossthe surface of the metallic glass film. The
tip interacts with the surface of the glass,8© 2011 APS

Nanoscale variations in the viscoelasticity of metallic glasses can help explain how
they form and break

Plot of the phase changes seen as a nanoscale tip is moved over the surface of a metallic glass, giving an
indication of variations in the surface’s viscoelasticity. The width of the image is around 200 nanometers.

thus allowing the viscoelasticity-induced
energy dissipation of the material underneath the tip to be calculated fromthe phase change of the tip vibration.
In addition, the topography of the glass
surface is measured at the same time.
Chen and co-workers found that theviscoelasticity of their metallic glass film
was not uniform, but instead varied byaround 10% over distances of 3 nanometers (see image).
In comparison, the same variation infilm height occurred over distances ofaround 9 nanometers. The difference
between these two numbers supports theinterpretation that the phase data reflects
inherent viscoelasticity, and is not related
to surface roughness.
Heterogeneous viscoelasticity suggeststhat there are regions of the metallic glassthat are more loosely packed than others,
which may help scientists to understandhow metallic glasses break and form.
Regions of higher viscoelasticity, forexample, are expected to deform morestrongly under applied mechanical stress.
“Our data bridges the gap between
atomic modeling and macroscopic
models of metallic glasses,” says Chen.
“In particular, it may help us understandhow metallic glasses undergo the transition to liquid-like phases.”

1. Liu, Y. H., Wang, D., Nakajima, K., Zhang, W.,
Hirata, A., Nishi, T., Inoue, A. & Chen, M. W.
Characterization of nanoscale mechanicalheterogeneity in a metallic glass by dynamic
force microscopy. Physical Review Letters106, 125504 (2011).

AIMResearch 2011

Research highlights

Magnetic memory

Less friction, lower power
A manganese–gallium alloy offers the perfect combination of properties for futuremagnetic memory
Magnetic materials continue to be thedominant storage system for computers.
The continuing demand for increased
storage densities has resulted in eversmaller magnetic bits, but as the bits become smaller, the long-term stability ofthe stored data begins to suffer. In the
search for novel materials with enhanced
long-term magnetic stability, a team led
by researchers from the WPI-AIMR1
has now discovered that an alloy ofmanganese and gallium is not only astrong magnet but also has switchable
magnetization with low loss — a key
requirement for fast, low-power nonvolatile magnetic memory.
There are two important requirements for magnetic memory. One is thestability of the magnetic orientation of adomain, a property known as magnetic
anisotropy. High magnetic anisotropy
is needed to ensure that information, in
the form of magnetic orientation, can beretained. The other property is magnetic
friction, which describes the losses associated when changes are made to themagnetization direction. “The larger themagnetic friction, the higher the electric
power required to record digital information,” explains Shigemi Mizukami
from the research team.
Similar to any other friction process,magnetic friction can be measured
through the slowing of motion. Here,it is the slowing of the precession ofmagnetization around an axis, similar
to the movement of a spinning top whenknocked off center (see image). And likespinning tops, this magnetic precession
can be set in motion through an external
force — in this case by an ultrashort laser
pulse. The slowdown of the precession
after a given amount of time can be

AIMResearch 2011

Probe
pulse

MnGa

Mn3Ga

Pump
pulse

Mn

Mn
Ga

The slowdown of spin precession (blue arrows) of manganese atoms in a manganese–gallium (Mn–Ga) alloy
can be pumped and probed with two ultrashort laser pulses. The low magnetic friction and high magnetic
anisotropy of this alloy may lead to the next generation of computer memory.

probed by a second laser pulse, whichallows the magnetic friction coefficient
to be calculated.
So far, all materials with high magnetic anisotropy had also shown a large
magnetic friction coefficient. For thesemanganese–gallium alloys, however, theresearchers found the magnetic friction
to be surprisingly low.
Theoretical calculations indicate that
this reduced friction is caused by a very
low density of available electronic statesat the topmost electron energies in thematerial. This means simply that there
are relatively few empty states available
for electrons to move into as a consequence of magnetic scattering, creating
a bottleneck through which magnetic

friction is suppressed. This discovery offers unique promise for future magnetic
random-access memory devices.
“Other than this alloy, there are nomagnetic materials that show both low
magnetic friction and high magnetic
anisotropy,” comments Mizukami. “Thiscombination of properties will be key indeveloping a replacement for existing
computer memories.”
1. Mizukami, S., Wu, F., Sakuma, A., Walowski, J.,
Watanabe, D., Kubota, T., Zhang, X., Naganuma,
H., Oogane, M., Ando, Y. & Miyazaki, T. Long-lived
ultrafast spin precession in manganese alloys
films with a large perpendicular magnetic
anisotropy. Physical Review Letters106, 117201 (2011).

9

Research highlights

Nanomaterials

Cool cubes forcatalytic converters
Out of the array of rare earths and precious metals that fill automobile catalytic
converters, a compound known as cerium oxide (CeO2) plays a special role.
The amount of oxygen inside an engine’s
combustion chamber determines theamount and composition of emissions
that result from burning gasoline.
Because CeO2 can both take in and release oxygen atoms without decomposing, this material is critical in balancing
oxygen within the catalytic converter
to bring emissions to their lowest levels
possible. The emission-cleaning capacityof the bulky CeO2 crystals currently usedin catalytic converters, however, is heldback by the limited amount of oxygenthat can be stored on their surfaces.
Now, using organic molecules toprecisely control CeO2 crystal growth,Tadafumi Adschiri from the WPI-AIMR
and co-workers have prepared CeO2‘nanocubes’ that display almost triple
the oxygen storage capacity of typicalCeO2 crystals1.
To produce these unique box-shaped
crystals, the team turned to a techniqueknown as supercritical hydrothermal
synthesis. First, a CeO2 precursor, a shorthydrocarbon chain and a water solvent
were locked together in a pressureresistant chamber and then heated to
400 °C. At supercritical temperatureand pressure conditions, the organic
molecules mix homogenously with themetal centers in aqueous solution, andattach to the most reactive faces of small
CeO2 crystals, hindering growth in that
direction. Transmission electron microscopy showed that this method generated
distinct CeO2 cubes less than ten nanometers across (see image). Testing theoxygen storage capacity of the ultrasmall

10

50 nm
Transmission electron microscopy image of 10 nanometer-wide CeO2 nanocubes

cubes revealed surprising temperaturedependent properties.
Whereas conventional irregularshaped CeO2 crystals only take in oxygen
when heated to 400 °C, Adschiri’s nanocubes adsorbed significant amounts ofoxygen at a much lower 150 °C, indicating a much higher catalytic activity.
“Oxygen storage capacity is directly
related to the mobility of oxygen in amaterial,” says Adschiri.
Normally, metal oxides need hightemperatures to make oxygen atoms
travel through their crystal framework.
But because the CeO2 nanocubes exhibit
high mobility at lower temperatures,
these compounds could potentiallyclean up emissions over a wider range
of operating conditions. This could be aboon for vehicles and reduce the amountof precious metals used for catalytic
emission cleaning.
Adschiri notes that controlling the
growth of crystals by manipulating
their exposed surfaces is the key totuning the catalytic activity of CeO2.
The researchers are now exploring how
other capping molecules and different
supercritical reactions conditions canlead to completely new methodologies
for catalyst fabrication.
1. Zhang, J., Kumagai, H., Yamamura, K., Ohara,S., Takami, S., Morikawa, A., Shinjoh, H.,
Kaneko, K., Adschiri, T. & Suda, A. Extra-lowtemperature oxygen storage capacity of CeO2
nanocrystals with cubic facets. Nano Letters11, 361–364 (2011).

AIMResearch 2011

© 2011 ACS

Cerium oxide ‘nanocubes’ that store more oxygen at lower working temperatures
promise to make automobile emissions cleaner

Research highlights

Sustainable chemistry

Made of greener stuff
Fabricating catalysts into robust, nanoporous metallic glasses eliminates leachingproblems during carbon coupling reactions
Convincing two organic molecules toconnect through the formation of acarbon–carbon bond is never straightforward. The discovery that precious
metals such as palladium can catalyze
precisely such coupling reactions under
mild conditions led to revolutionary
advances in a range of fields, including
the synthesis of pharmaceuticals andorganic semiconductors. Unfortunately,
palladium catalysts are toxic, expensive
and difficult to separate completely fromthe final product. Handling issues can be
circumvented through the use of a solid
support, but gradual leaching of themetal into the surrounding solution cancontaminate reactions.
Naoki Asao, Yoshinori Yamamotoand colleagues from the WPI-AIMR at
Tohoku University1 have now developed
a solid palladium-based ‘metallic glass’
that can repeatedly catalyze carbon
coupling reactions with negligible leaching of the catalyst into the solvent. And
thanks to an electrochemical fabrication
technique that permeates the metallic glass with a uniform, nanoporous
framework, the team’s recyclable catalyst
shows excellent activity. Together, thesetwo developments represent criticalimprovements for industries facing
demands for safer, more sustainablechemical procedures.
Metallic glasses are stiff, strong alloys
made by quickly cooling a mixture of
atoms — in this case palladium, nickel
and phosphorus — into an amorphoussolid. The very dense packing of atoms
in these materials affords them highresiliency, but the bulk metallic glasses
are not catalytically active because onlya small proportion of palladium atoms
are sufficiently exposed to interact

AIMResearch 2011

Nanoporous palladium
Benzene-type
compounds

Hydrogen
Boron
CarbonOxygenIodineProduct

A nanoporous palladium material (center) that catalyzes coupling reactions between benzene-type
compounds can be used many times without breaking down or losing activity

with organic reagents. The team solved
this problem by exploiting one of the‘noble’ properties of palladium metals — a strong resistance to electricalcorrosion. Asao explains that dipping apalladium–nickel–phosphorus metallic
glass into an electrochemical etching solution dissolves the nickel andphosphorus atoms, while the palladium
atoms agglomerate into a clustered,
three-dimensional network. Due to thehomogenous composition of the initial
alloy, the resulting catalyst has a uniform
distribution of pores of about 30 nanometers in diameter.
When the team performed a typicalcoupling reaction between two benzene rings bearing iodine and boron
functional groups, they saw that thenanoporous catalyst gave the desired
product in close to maximum yield (seeimage). Even after reusing the catalyst

four times, the coupling proceeded
extremely efficiently.
Further analyses also revealed thatthe amount of palladium lost into
solution during the reaction was lessthan 0.0005% of the precious metal ineach cycle.
“Contamination with palladium must
be avoided, especially when the products
are medicines,” says Yamamoto. “Ourresults demonstrate one way to solve theleaching problem, and give us hope that
more innovations are possible, allowing
nanoporous palladium to be developed
as a robust ‘green’ catalyst.”
1. Tanaka, S., Kaneko, T., Asao, N., Yamamoto, Y.,
Chen, M., Zhang, W. & Inoue, A. A nanostructured skeleton catalyst: Suzuki-coupling with areusable and sustainable nanoporous metallic
glass Pd-catalyst. Chemical Communications
47, 5985–5987 (2011).

11

Research highlights

Spin electronics

Magnetism under control
A switchable magnetic semiconductor that operates at room temperature could leadto enhanced electronic devices
The ability to switch the magnetic
properties or electron ‘spin’ of a semiconductor in a similar way to charge
in conventional devices opens up new
possibilities for fast, low-power data
storage and ‘spintronics’ applications.
The magnetic semiconductor materials
needed for such applications at room
temperature, however, have proved
elusive as most magnets are either metals or insulators. Now, researchers fromthe WPI-AIMR in collaboration withcolleagues from the University of Tokyo
have developed a magnetic semiconductor system with controllable ferromagnetism at room temperature1.
The compound studied — titanium
dioxide containing a small amount of
the magnetic element cobalt — has
previously been suggested by some ofthe same researchers to be ferromagnetic
at room temperature. “We have now unambiguously demonstrated not only thattitanium cobalt dioxide is a ferromagnetic semiconductor, but also that it canbe used for transistors using switchable
ferromagnetism,” says Masashi Kawasaki
from the research team.
The researchers achieved control ofthe magnetic properties of the material
by modulating the density of electrons
it contains: an accumulation of electrical charge enhances its magnetic properties, while the depletion of charge
turns the magnetization off (see image).
In previous studies, injecting sufficientcharge into the material to drive thisswitching functionality had met withlimited success because the voltages required were too high, destroying
the sample.
To achieve high charge concentrations,the researchers used a recently developed

12Electrical charge induces magnetism in the semiconductor titanium cobalt dioxideapproach that involves delivering electrical charge into the material using a liquid
electrolyte rather than by the solid-state
capacitor used previously. Such electrolytes are known to carry large quantities
of charge, which has led to their use forelectrical energy storage in applications
such as supercapacitors in electrical cars.
The use of a liquid electrolyte resulted
in a system for which only a few volts
were needed to switch the magnetism oftitanium cobalt dioxide on and off.
The development of a magnetic
semiconductor providing switchable
magnetic properties at room temperature offers intriguing possibilities forhigh-performance devices that use not
only the charge of an electron but also its‘spin’ or magnetic properties. Although

the use of a liquid electrolyte has its
practical limitations and cannot, forexample, be integrated easily on computer chips, Kawasaki is confident suchhurdles can be overcome. “There are two
possibilities. One is to search for a morepractical way of switching, and the otherto look for applications where liquids are
suitable. The important point is that weknow that switching can be achieved in
the first place.”

1. Yamada, Y., Ueno, K., Fukumura, T., Yuan, H.
T., Shimotani, H., Iwasa, Y., Gu, L., Tsukimoto,S., Ikuhara, Y. & Kawasaki, M. Electricallyinduced ferromagnetism at room temperaturein cobalt-doped titanium dioxide. Science
332, 1065–1067 (2011).

AIMResearch 2011

Research highlights

Single-molecule spectroscopy

A new gold standard?

Wrinkly films of nanoporous gold
just 100 nanometers thick make anexcellent surface for ultra-high sensitivity chemical diagnostics, a team of
WPI-AIMR researchers led by Mingwei
Chen has shown1. The nanoporous surface allows even a single molecule of ananalyte to be detected using a techniqueknown as surface-enhanced Raman
spectroscopy (SERS).
Raman spectroscopy takes advantageof the fact that many molecules interact
with light and scatter it in a characteristic way. Because different molecules
scatter light at different wavelengths, thetechnique can be used to identify an unknown chemical. For many molecules,
however, the scattering effect is very
weak, which means that the scattered
light is extremely difficult to detect.
The nanoporous gold surface prepared by Chen and his colleagues
amplifies the Raman effect to an extent
that SERS can be used to detect thepresence of single molecules. OtherSERS substrates with this capability
have been prepared in the past, but theytend to have drawbacks such as low
stability or poor reproducibility. “In our
research, we developed a controllable
method to fabricate large-scale, stable
and reproducible SERS substrates,” says
Ling Zhang, a postdoctoral fellow of theresearch team.
To fabricate their wrinkled gold substrate, the researchers attached flat gold
sheets with nano-sized pores onto a
pre-strained polymer substrate. Heating
caused the polymer to shrink, which inturn caused the overlying nanoporous
layer of gold to wrinkle up (see image).
Different wrinkle structures wereobtained by varying the size of the

AIMResearch 2011

© 2011 ACSThin wrinkled sheets of nanoporous gold make particularly suitable surfaces for
single-molecule detection

500 nmA scanning electron microscopy image of the wrinkled Raman-active gold surface

nanopores, with the best results obtained using 26-nanometer holes.
Key to the Raman-enhancing effect of
the gold surface is the way that its threedimensional wrinkled texture interacts
with light. The nanogaps formed on thewrinkled surface allow light to induce
collective oscillations of electrons atparticular points or ‘hotspots’ on thesurface by an effect known as surface
plasmon resonance. The plasmonic
effect is known to amplify the Raman
scattering signals of nearby moleculeson the surface, but this is the first timethat such a plasmonic-based surface has
been produced reliably.
The local SERS enhancement factor at‘hotspots’ on the wrinkled gold surface

can be larger than 100 million, the researchers showed. “This is comparable
to the best Raman-active nanomaterials
and enables single-molecule detection,”says Chen.
The team is continuing work to improve the performance of their gold surface for practical analytical chemistry
applications. “We are now optimizing
the chemical composition and structureof the wrinkled films to further increase
the density and local enhancement factors of the ‘hot spots’,” says Chen.
1. Zhang, L., Lang, X., Hirata, A., & Chen, M.
Wrinkled nanoporous gold films with ultrahighsurface-enhanced raman scattering enhancement. ACS Nano 5, 4407–4413 (2011).

13

Research highlights

Superconductors

Dirac cones come in pairs
The superconductor compounds known as pnictides have a double Dirac coneenergy structure that dramatically affects their magneto-transport properties
The Dirac cone is a surface that describesin theoretical terms the unusual electrontransport properties of materials likegraphene and the even newer class ofmaterials known as topological insulators. Scientists can both predict andmeasure the existence of a Dirac conefrom the relationship between electronenergy and momentum, and throughsuch studies have confirmed that theclass of iron-based superconductor compounds known as pnictides have thischaracteristic energy structure. Katsumi
Tanigaki and colleagues from the
WPI-AIMR and Tohoku University have
now demonstrated the effect that such
Dirac cones can have on the electrontransport properties of these materials1.
The researchers investigated samplesof the pnictide Ba(FeAs)2. There is a fundamental difference between the Diraccones of the pnictides and graphene,
however. “The Dirac-cone state of graphene derives from a single ‘π-electron’band, while the Dirac-cone states ofBa(FeAs)2 are made from multiple‘d-electron’ bands,” explains Tanigaki.
This multi-band origin creates agreater chance for the development of amore versatile Dirac-cone structure (seeimage), depending on the material.
The main observable effect of a Diraccone is a linear relationship between
resistance and applied magnetic field,
or magnetoresistance, above a certain‘crossover field’, below which the relationship is parabolic. These curves
can be well explained using existingmodels as due to the effect of Landaulevel splitting.
Under a magnetic field, the electronenergy is split into Landau levels, thelowest of which exhibits linear behavior,

14Electronic band structure of Ba(FeAs)2, showing the Dirac cones (circles)

similar to the feature described by the
Dirac cone. On increasing the magnetic
field, the level splitting increases and allof the electrons move to this lowest level,
which makes the magnetoresistanceeffect linear. Importantly, this should
occur at magnetic fields easily accessibleusing existing magnets.
A crucial conclusion that can be
drawn from the detailed analysis of thedata is that the observed magnetoresistance must be caused by a combinationof two Dirac cones, one for electrons
and also one for their opposite number, holes — a finding that had notbeen anticipated.
Tanigaki believes that the results could
be important for superconductivity, as
engineering the compounds to enhance

the contribution of Dirac cones could
lead to superconductors that operate at
higher temperature.
There could also be practical consequences. “High-mobility field-effective
transistors are made using superlattice
structures in III-V semiconductors.
However, we can hope in the futurethat high-mobility transistors can also
be constructed from compounds with
Dirac-cone states,” says Tanigaki. The
observed linear magnetoresistance could
also lead to highly sensitive magnetic
field sensors.
1. Huynh, K. K., Tanabe, Y. & Tanigaki, K. Bothelectron and hole Dirac cone states in Ba(FeAs)2
confirmed by magnetoresistance. PhysicalReview Letters 106, 217004 (2011).

AIMResearch 2011

Research highlights

Superconductors

Taking charge of the future

Since the discovery of superconductivity more than a hundred years ago, newsuperconductors have typically been
discovered by looking for new compounds that, when cooled to extremely
low temperatures, show a vanishingelectrical resistance. Masashi Kawasaki
and colleagues from the WPI-AIMR
in collaboration with researchers fromthe University of Tokyo have now devised an entirely new way of searchingfor superconductors — by artificiallyintroducing large amounts of electrical charges into known materials1.
Using the approach, the researchers
have discovered superconductivity inthe compound potassium tantalumoxide (KTaO3).
Superconductivity arises from a pairing of electrons in a material, whichmakes them immune to external disturbances such as scattering off atoms
in the crystal. Given this key role offree electrons, many materials could bemade to superconduct by introducing
a surplus of free electrons by chemical‘doping’. Unfortunately, however, there
are constraints on the maximum chargethat can be introduced in this way.
The alternative developed by
Kawasaki and his co-workers is tointroduce the electrons externally. Thiscan be done through the use of an ionicliquid, which is able to transport large
amounts of charge. By bringing theionic liquid into contact with the surface
of an electrical circuit containing thematerial (see image), an electric double
layer is formed at the material–liquidinterface. Applying an electrical voltage
then separates the charges. On lowering the temperature, the researchers
found that the compound, in this case

AIMResearch 2011

© 2011 M. Kawasaki

A fundamentally new way to search for superconductivity using ionic liquids could
lead to the discovery of entirely new classes of superconductors

Photograph of the electric double layer transistor with a drop of ionic liquid for testing for superconductivity
in KTaO3

KTaO3, transformed from its original
insulating state into a semiconductor,
a metallic conductor and eventuallya superconductor.
“Through this ionic liquid-based
method, we achieved a charge density
in the material about ten times higher
than that achievable by conventional
methods,” says Kawasaki.
Superconductivity had not previously
been observed in KTaO3, and although
the phenomenon was observed atvery low temperature, the appearanceof superconductivity is only possible
because of the high electrical charge
densities. The real potential of this newtechnique therefore lies in the discovery
that superconductivity can be induced
in materials under circumstances

not investigated previously. “We do
not have the same limitations as withchemical doping,” comments Kawasaki.
“There are many compounds that could
become superconducting by providing
sufficient charge carriers but which havenot been examined yet.”In particular, while the discovery ofsuperconductivity in KTaO3 is exciting in
itself, the approach used to make the discovery is more exciting for its potential
to uncover superconductivity at higher
temperatures than achieved so far.
1. Ueno, K., Nakamura, S., Shimotani, H., Yuan, H.
T., Kimura, N., Nojima, T., Aoki, H., Iwasa, Y. &Kawasaki, M. Discovery of superconductivity in
KTaO3 by electrostatic carrier doping. Nature
Nanotechnology 6, 408–412 (2011).

15

Research highlights

Photovoltaics

Making light work of organic
solar cells
A novel method for producing functionalized fullerenes could lead to lower-costorganic solar cells
With growing demand for renewableenergy sources, devising new methods
to improve the efficiency of photovoltaic materials is a key challenge in the
production of next-generation solar
cells based on organic materials rather
than silicon. A team led by Tienan Jin
from the WPI-AIMR in collaboration
with researchers from China have now
developed a novel strategy to produce
organic solar cells using functionalized
carbon ‘fullerenes’ with high yield andat low cost1.
Photovoltaic cells generate electricity
from light based on a system of chargetransfer between electron donor and acceptor molecules. Fullerenes — soccer
ball-like spheres of carbon atoms — arewidely used as an acceptor moleculein organic solar cells in the form ofphenyl-C61-butyric acid methyl ester(PCBM), but this complex moleculeis expensive to make and attempts to
reduce production costs have so far
met with limited success. Jin and his
co-workers turned to the naturally
occurring fullerene C60 as a lower-cost
alternative to the C61 derivative.
Functionalizing C60 to achieve the samelevel of electron acceptor performance,
however, required the development of a
new synthesis strategy.
The researchers functionalized theC60 fullerene (pictured) by grafting on
alkyl chains. This type of modification
has been performed in the past using
magnesium- or lithium-based reagents,
but these reactions often result inover-alkylation. Milder, more selective
conditions are needed to produce themono-functionalized fullerenes that are
most suitable for use in organic solar
cells. “We have previously developed a

16

C60 is a spherical form of carbon that can be functionalized for use in photovoltaic applications

number of transition metal-catalyzed
molecular transformations at carbon–
carbon multiple bonds, so we investigated whether we could functionalize
C60 in the same way,” explains Jin.
After an exhaustive search of possible
catalysts and reaction conditions, theresearchers found that a cobalt-based
compound was the most efficient catalyst for this grafting reaction. Adding
the C60 and an alkyl halide compound
to a solution of the cobalt catalyst anda manganese reducing agent gave themono-alkylated C60 fullerenes in 88%
yield in 2 days. Using this efficient procedure, Jin and his colleagues were able
to produce fullerenes bearing a zinc
porphyrin, a branch-like dendrimer,and even another fullerene to afford
a fullerene dimer or ‘dumbbell’ — allof which are difficult to synthesize by
previous methods.
A simple organic solar cell with a bulk
heterojunction structure constructedusing the new fullerene derivatives
achieved higher solar-to-electricity
conversion efficiency than a comparable
device prepared using the conventional
PCBM electron acceptor. “Based on thispromising result, we plan to design andsynthesize other new fullerene derivatives with possible photovoltaic applications,” says Jin.
1. Lu, S., Jin, T., Bao, M. & Yamamoto, Y.
Cobalt-catalyzed hydroalkylation of [60]fullerene with active alkyl bromides: selective
synthesis of monoalkylated fullerenes.
Journal of the American Chemical Society
133, 12842–12848 (2011).

AIMResearch 2011

Research highlights

Catalysis

A tale of two metals
A nanoporous palladium-nickel catalyst shows promise for improved catalytic
performance in fuel cell applications
Platinum-based materials are traditionally the catalysts of choice for incorporation in fuel cells. In recent years,
however, palladium-based materials
including bimetallic alloys have become
more attractive due to their high electrocatalytic activity in key oxidation andreduction reactions.
On the nanoscale, catalysts formed
from palladium or platinum nanoparticles have shown high performanceowing to their large surface areas
and outstanding mechanical andelectrical properties.
Mingwei Chen at the WPI-AIMR at
Tohoku University, Japan, and colleagues
have now prepared a bulk palladiumnickel alloy with a nanoporous structurethat combines some of these advantages
to produce an easily recyclable, low-costand high-performance catalyst1.
In a series of electrochemical studies,
they have demonstrated that their novel
nanoporous Pd–Ni alloy (np-PdNi)
is a superior catalyst for small molecule electro-oxidation and oxygen
reduction reactions.
The np-PdNi material is made byelectrochemically dealloying a Pd20Ni80
bimetallic alloy in a sulfuric acid solution. Nickel partially leaches out of thealloy through control of the etchingpotentials. The structure of np-PdNicomprises crystalline metallic ligaments
and nanoporous channels in a bicontinuous arrangement (see image).
A combination of X-ray photoelectron spectroscopy and ion etching
techniques reveals that the distributionof nickel within the metallic ligaments
varies depending on depth — the core
is nickel-rich, whereas the shell ispalladium-rich.

AIMResearch 2011

50 nm
A scanning electron microscopy image of the nanoporous PdNi alloys

For the electro-oxidation reactionsof methanol or formic acid, np-PdNi
shows a higher catalytic activity than
nanoporous pure palladium and commercial nanoparticulate Pd–C catalysts.
In addition, the onset potential forcatalytic activity is more negative for
np-PdNi than for nanoporous Pd, which
implies that the kinetics of the electrooxidation reaction are enhanced.
The np-PdNi material also exhibits
excellent electrochemical stability —after 500 cycles of the electro-oxidationof methanol, the loss of electrocatalytic
activity is only around 8%, a better result
than that of commercial Pd–C catalysts.
“The current catalytic performanceof the np-PdNi in the oxygen reduction
reaction is just comparable to commercial platinum catalysts,” says Chen. “In
the future, we need to further optimize
the morphology and composition of the

np-PdNi to improve catalytic performance so that it surpasses the expensive
platinum catalyst.”
Potential applications of the material include the development of various
green energy devices, including commercial fuel cells, hydrogen sensors andnanostructured electrodes.
Chen and his co-workers are currently investigating how the control ofdealloying potentials and alteration of
the alloy precursors could be further
extended to make an even wider rangeof nanoporous materials with compositions that can be finely tuned.
1. Chen, L., Guo, H., Fujita, T., Hirata, A, Zhang, W.,
Inoue, A. & Chen, M. Nanoporous PdNi bimetallic
catalyst with enhanced electrocatalytic
performances for electro-oxidation and oxygen
reduction reactions. Advanced Functional Materials Published online: 8 Sep 201117

Research highlights

Oxide interfaces

One atom at a time
Scanning tunneling microscopy reveals unique insights into the atom-by-atom
growth of transition metal oxides on substrates

18

3 nm

film
interfacesubstrate© 2011 ACS

The combination of two similar objects
has the potential to create a completely
different material. In recent years, theheterostructures of transition metaloxides have demonstrated a range of
surprising properties, such as the interface between lanthanum aluminate andstrontium titanate. Both materials are
insulators in their bulk form, yet also
show very high conductivity and undercertain conditions can even becomesuperconductive. Given the wide rangeof compositions these oxides can span,
it is expected that more functionalities
can be discovered — and possiblyused in devices — through judicious
combinations. But to achieve this, it isessential to understand and control themorphology and electronic structure of
the interfaces at the atomic scale. So far,however, interface formation has been
mainly studied at the unit-cell level.
Ryota Shimizu, Taro Hitosugi andcolleagues at the WPI-AIMR at Tohoku
University and other institutions inJapan have now zoned in on atom-byatom growth through their constructionof a high-resolution scanning tunnelingmicroscopy combined with a pulsed
laser deposition system1. This device
enabled the team to closely investigate
the formation of very thin strontium
titanate films at atomic resolution2.
The researchers began their investigation with the homo-epitaxial atom-byatom growth process of a perovskite
material, strontium titanate. Using
pulsed laser deposition, they grew astrontium titanate film on a substrate of
the same material that has a specific perfectly ordered structure. “We found that
this specific surface can be prepared ina wide range of oxygen partial pressures

A typical scanning tunneling microscopy image acquired on the strontium titanate surface (top) and aschematic model of an interface composed of perovskite oxides (bottom)

in a reproducible manner. This is why
strontium titanate is an ideal substrate
to serve as a model, which will then enable us to monitor at the atomic level thegrowth processes of perovskite oxides
more generally,” explains Shimizu.
After the films were grown, the teamobserved the formation of island terraces with an atomic structure identicalto that of the substrate. In particular, theresults showed atomic-level coherency
between the substrate and the thin film,
whereby the substrate imposed its morphology on the newly grown film.
The results offer potential growthfor other materials as well. “Our teamis now conducting growths of otheroxide materials, such as strontiumoxide, lanthanum aluminate andmanganite, to unveil the growth process
and interfacial formation between different materials at the atomic scale,” says
Shimizu. “These investigations may leadto the preparation of new heterostructures, or high quality thin films withexotic multifunctionality.”
1. Iwaya, K., Shimizu, R., Hashizume, T. & Hitosugi,
T. Systematic analyses of vibration noise of avibration isolation system for high-resolution
scanning tunneling microscopes. Review of
Scientific Instruments 82, 083702 (2011).
2. Shimizu, R., Iwaya, K., Ohsawa, T., Shiraki, S.,
Hasegawa, T., Hashizume, T. & Hitosugi, T.
Atomic-scale visualization of initial growth ofhomoepitaxial SrTiO3 thin film on atomicallyordered substrate. ACS Nano 5, 7967 (2011).

AIMResearch 2011

Research highlights

Nanoclusters

Steel that breaks the rules

Following recent events, such as thenuclear accident at the Fukushima
nuclear power plant triggered by the2011 Tohoku earthquake, worldwide
pressure is mounting to develop safer
nuclear power facilities. The search is
on for stronger, more durable materials
with which to build structures that areable to endure extremely harsh or toxic
environments. Some of the most promising candidates are ‘oxide-dispersionstrengthened’ (ODS) steels. These ODS
steels contain tiny nanoclusters withina steel matrix, and show an outstanding resistance to radiation damage andhigh temperatures — yet little is known
about the internal atomic structures ofthese nanoclusters.
Using the latest microscopy technology, Mingwei Chen and Akihiko
Hirata, together with colleagues at the
WPI-AIMR at Tohoku University, Japanand the City University of Hong Kong,
have now analyzed the atomic structures of oxide nanoclusters less than
4 nanometers in size found in ODS steels(see image), and have uncovered somesurprising results1.
“We recognized that understanding
the atomic structure of the nanoclusters is the most important task in the
research of ODS steels,” explains Chen.
“This underlying crystal structure plays
a crucial part in the amazing strength ofthese materials in harsh environments.”
The researchers used Cs-correctedscanning transmission electron microscopy, with a resolution of about
0.1 nanometers, to identify complex
atomic structures within the tiny oxide
nanoclusters. The high level of magnetism present in the steels represented achallenge. “The magnetic steel matrix

AIMResearch 2011

© 2011 M. W. Chen

Atomic imaging of nanoclusters gives greater insight into the remarkable strengthand durability of strengthened steel

Illustration of an oxide nanocluster in oxide-dispersion-strengthened steel. Defects in the nanocluster
crystal structure might increase affinity with the steel matrix, resulting in the material’s remarkable strengthand durability.

makes it difficult to image the clusters,”
explains Chen. “We minimized the magnetic effect by carefully preparing ultrathin samples about 5 nanometers thick.”
Perhaps the most surprising result
from the study is that the nanoclusters
have very defective rock salt crystal(NaCl-type) structures, yet are incredibly stable at high temperatures. “This isa pretty interesting phenomenon,” states
Chen. “We know from thermodynamics
that, in perfect crystal structures, lower
total energy leads to a more stable phase.
However, the nanoclusters in the ODS
steels appear to show the opposite.”
The data revealed that the atomic
structure of small nanoclusters andlarger nanoparticles present in the ODS
steels both featured NaCl-like structures, but with important differences.

“The unstable, coarsened nanoparticles
possess a near perfect crystal structure,
whereas the stable nanoclusters have avery defective one with a high percentage of vacancies,” explains Chen.
The researchers believe that the defective structure might encourage greateraffinity between the nanoclusters and thesteel matrix, increasing overall stability
under high temperatures and neutronradiation. The team intends to further
examine other nano-strengthened steelsin the near future.

1. Hirata, A., Fujita, T., Wen, Y. R., Schneibel, J. H.,
Liu, C. T., & Chen, M. W. Atomic structure ofnanoclusters in oxide-dispersion-strengthened
steels. Nature Materials DOI 10.1038/
NMAT3150 (2011).

19

Research highlights

Micromirrors

Metallic glasses begin to shine

Silicon is traditionally the material of
choice in micromechanical innovations.
Complex sculptures are now fabricatedonto silicon chips for new types of microscale devices, tiny silicon cantilevers
are widely used as acceleration sensors,and micromirrors can be used to scan alight source across a larger area, such as
in laser projectors or in endoscopes. The
brittleness of silicon, however, limits thepossible range of its applications.
Jae-Wung Lee, Yu-Ching Lin andcolleagues from the WPI-AIMR in collaboration with researchers from otherinstitutions in Japan and Germany,
have now used hard metallic glasses as a
tougher alternative to silicon in the development of enhanced micromirrors1.
Although they look like any othermetal, metallic glasses are not very
different in structure from ordinary
window glass. Unlike crystals, whichhave an ordered structure, the atoms ofmetallic glasses are randomly arranged,
making them much stronger than silicon, or even some steels. They can bearheavier loads without starting to deform,
and are thus ideal for micromechanicaldevices in which small components arerepeatedly subjected to strong forces.
Even after many operating cycles, metallic glasses remain largely intact.
The research team constructed a mirror structure by placing a round plate
between two torsion bars that form theaxis for the mirror’s movements (seeimage). The torsion bars are entirely
made of metallic glass, while the plateis a metallic glass film stabilized by asilicon frame. The glasses’ composition
included substantial iron content togive magnetic properties. “This makes
it possible to actuate the mirror by an

20© 2011 Optical Society of America (left image)The mechanical strength of metallic glasses makes them ideal components for
micromechanical devices, such as rotating mirrors

Turning metallic glass mirrors. The mirror surface and torsion axes are fabricated from a single metallic glass
film, with the mirror film supported by silicon. The photos show the turning mirror (left) along with a close-upof the torsion axis (right).

external magnetic field, which simplifies
the design and fabrication process of the
micromirror,” explains Yu-Ching Lin.
The metallic glass has good elasticity and strength, allowing the mirror
to reach large tilting angles. When inresonance with an oscillating external
magnetic field, the mirrors followed
the field and rotated more than 300
times per second without undergoing any damage. Tilt angles of over
70 degrees were demonstrated in thisdynamic mode, and in larger static
magnetic fields, the mirrors reached up
to 270 degrees. However, further development is needed.

“Many compatible micromechanical fabrication techniques for metallic
glasses are still missing,” says Lin. “Ournext attempt is to develop etching technologies for metallic glasses to realize
smaller and more versatile patterns.”
But with such unique mechanicalproperties, metallic glasses are poised
to play a more significant role in micromechanical devices in the future.
1. Lee, J.-W. Lin, Y.-C., Kaushik, N., Sharma,
P., Makino, A., Inoue, A., Esashi, M. &Gessner, T. Micromirror with large-tilting angle
using Fe-based metallic glass. Optics Letters36, 3464-3466 (2011).

AIMResearch 2011

IN THE SPOTLIGHT
The WPI-AIMR has grown rapidly since its inauguration in 2007,
now with over 120 leading researchers from all over the world,
including 31 internationally renowned principal investigators
who are charged with pioneering new and innovative breakthroughs in materials science. The institute is also active indeveloping young, promising researchers with a focus on strong
cross-disciplinary collaboration and creativity. AIMResearch
spotlights these talented researchers of the present and future,detailing their daily research activities and scientific ambitions.

IN THE SPOTLIGHT

INTERVIEW WITH DIRECTOR AND DEPUTY DIRECTOR

Published online 30 January 2012Materials research like none other
Current WPI-AIMR director Yoshinori Yamamoto and deputy director Motoko Kotani reflect on the challenges facedby the institute to date, and share their vision on the institute’s next stage of development.

The WPI-AIMR recently celebrated its
fourth anniversary. What are the mostnotable research achievements made at theinstitute since it opened?
Yamamoto: The WPI-AIMR gathers awide variety of world-class researchers
under one roof to carry out cutting-edge
research across a range of topics in materials science, and we have published alarge number of papers in leading international journals. However, there aresome discoveries that particularly standout. For example, one of our young assistant professors, Seigo Souma, whoworks in Takashi Takahashi’s group, hasrecently made an extremely important
breakthrough in pure research in understanding the mechanism that underpins
the phenomenon of high-temperature
superconductivity (HTSC). At the WPIAIMR, we have built the highest resolution Angle-Resolved Photoelectron
Spectroscopy (ARPES) set-up in theworld, and Souma and his team have used
this to establish the important role thatelectron spin plays in HTSC. Anothernoteworthy result is the discovery of newmaterials by Terunobu Miyazaki’s groupwhich can be applied to so-called ‘normally-off ’ computers. As you know, conventional computers have to be switchedon all the time to work, but as their namesuggests, normally-off computers only
draw power when it is absolutely necessary for memory operations. It is expected that these normally-off computerswill consume up to 70% less power thanexisting machines.
Earlier this year the Mathematics Group,
under the direction of Professor Kotani, was22

Current director Yoshinori Yamamoto (left) and deputy director Motoko Kotani (right) discuss the past challenges
and achievements of WPI-AIMR and the future direction of the institute.

added to the existing four research divisions
at the WPI-AIMR. How is the new groupdeveloping and how is it expected to change
the way the institute operates?
Kotani: The Mathematics Group is alreadyworking actively with colleagues in othergroups, such as the Applied Mathematics
Forum at Tohoku University. We will soon
have three principal investigators, including myself, as well as two associate professors and three assistant professors, andour plan is to eventually add postdoctoral
researchers and PhD students who will use
mathematics to better explain the theoretical underpinning of the experimental work
carried out at the institute. We hope thatanalyzing materials science at the mostfundamental level will allow us to predict
the future direction projects should follow
to get the best results in the most efficient
way possible.
Yamamoto: A good example is Seigo
Souma’s work on HTSC. The standard
approach for this application would
be to carry out various trial-and-error

experiments and gradually move towards
more efficient superconductors. However,this can be an unreliable, expensive andtime-consuming approach. If we canincrease the accuracy of our theoreticalmodels for HTSC, it may help us to focus
on higher-performing systems that would
otherwise take us much longer to find.
The WPI-AIMR actively pursues new approaches to create a world-class research
environment. What steps have been taken
to achieve this and what challenges have you
faced along the way?
Yamamoto: Creating the right sort ofresearch environment is probably the biggest challenge we have ever faced. One of
the most concrete examples is the magnificent new research facility we are now
sitting in. Having all of our researchers
here under one roof is vital for carrying out‘fusion’ research.
Kotani: Our plan for the new building was
to feature at the very heart of the design
the idea of encouraging free discussion

AIMResearch 2011

IN THE SPOTLIGHT

Kotani: Currently we are focusing on
personalizing administrative support at
the WPI-AIMR. Previously it was difficultfor our researchers to find out whom toapproach for assistance, so now we are ensuring that the roles of support staff will be
more clearly delineated and identifiable.
Current director, Yoshinori Yamamotoand exchange. This is reflected in the
open-plan areas where researchers canmeet and talk informally over coffee, butwith a whiteboard in reach to aid discussion. In many Japanese universities, thiskind of informal meeting area is often considered a waste of valuable space, but for
us it is an indispensible part of the research
environment. Cultivating a new kind of
fusion research culture that can lead tonew breakthroughs and also challenge thestatus quo in Japanese universities is one of
the central aims of the WPI program as awhole, and as such it is vital to our successas an institution.
Yamamoto: Another big challenge we have
faced is how to create an environment thatis welcoming to overseas researchers. We
have implemented a number of initiatives
to help our non-Japanese staff and students.
For example, we have adopted English as
the official working language within thecenter to enable easier communication. We
are also building a new international housefor foreign students and staff.

The new WPI-AIMR Main Building

AIMResearch 2011

How was the WPI-AIMR affected by the2011 Tohoku earthquake and how well is it
recovering?
Yamamoto: The earthquake caused
widespread devastation and loss of lifein the Sendai area and the wider Tohoku
region. Immediately after the earthquake,
we briefly halted operations to checkthe damage and ensure the safety of ourstaff and students. Some of our overseas
members returned temporarily to theirhome countries; however, we were able toreassemble most of the teams within a few
weeks after the disaster and return to work,
although severe aftershocks continued forseveral weeks. Whilst the actual buildingsof the institute escaped largely unscathed,some of the facilities and equipment wereseverely damaged.
Kotani: Despite the heavy financial burden
from the earthquake, we were determined
to minimize its effect on our research output. We had to think creatively about how
we could best use the equipment that was
still intact, for example, by learning to use
our equipment in new ways. Some staff
took the opportunity to focus on analyzing
existing data and writing up papers while

Incoming director, Motoko Kotani

they were waiting for equipment to be
repaired or replaced. As a center, we felt avery strong sense of responsibility to people
in the Tohoku region to play our part in therebuilding effort, and the best way we could
do that was to continue our research.
Next year the WPI-AIMR will have newleadership as Professor Kotani takes over as
director of the institute. What plans does the
WPI-AIMR have for expansion in the next
5 years?
Yamamoto: The institute will probably remain at its current size of about 200
members. However, we still have to focus
on developing the WPI-AIMR so that it
can influence our university and others
in Japan. Institutions in East Asia need torethink their approach to learning andresearch in order to compete with thosein the USA and Europe. To address thisissue, we aim to set up institutions thatwill help transform the research culture ofJapanese universities.
Kotani: Our overarching research theme
at WPI-AIMR will be “Building the future
through materials”. We will also increasingly
use mathematics to improve the accuracy
and reliability of our theoretical models, andto improve the predictability and efficiencyof our experimental work. Through this
WPI-AIMR will become an unprecedented
model of research institute which combinesmathematics and materials sciences. Goingforward, I want the WPI-AIMR to becomea center like no other in the world, one that
attracts the very best and most ambitious
researchers from across the globe to develop
new materials that, rather than simply fulfilling a need, actually change the way we look at
the world around us.23

IN THE SPOTLIGHT

ROUNDTABLE INTERVIEW

Published online 26 September 2011

Tearing down the walls of research
Researchers at the WPI-AIMR share their perspectives on the benefits of cross-disciplinary collaboration and discuss
some of the latest advances in the design of novel hybrid metal catalysts and green technology applications.

As the technologies of the future
become more elaborate and morereliant on the convergence ofmultiple, often wildly dissimilar fields ofresearch, substantiating such cross-disciplinary collaboration as an integral partof the research culture has become more
important than ever. Bringing together
researchers from vastly different scientificbackgrounds to work together effectively
on the type of ‘fusion’ research that canlead to the next great innovation, however,requires more than casual collaboration.
When it was established in 2007, the
WPI-AIMR at Tohoku University set out
specifically to nurture fusion researchon innovative functional materials byadopting an organizational and research
structure that makes interdisciplinary
collaboration a natural part of the work
environment. After four years and a
total of 44 fusion research projects, theinstitute’s reputation for innovative, crossdisciplinary materials-oriented researchextends across the globe, attracting someof the world’s leading researchers inmaterials science.
Close-knit network of researchers
The WPI-AIMR is now home to 119 researchers, about half of whom are from

24

From left to right: Naoki Asao, Takeshi Fujita, Hongwen Liu, Koji Nakayama

countries other than Japan, and many
resolved to join the institute specificallybecause of its emphasis on innovative interdisciplinary research. “The fusion
research we are carrying out here is creating completely new research fields, so it
is much more than just simple collaboration,” says Naoki Asao, a professor at the
WPI-AIMR’s Soft Materials Group since2009. Asao carries out fusion research
aimed at developing nanostructured
hybrid metal catalysts. “Before coming
to the WPI-AIMR, I had never heard ofnanoporous materials during my careerin synthetic chemistry,” he says. The opportunity to collaborate with Mingwei
Chen, principal investigator of the Bulk
Metallic Glasses (BMG) Group, however,has enabled Asao to hone his expertise in
the production of nanoporous gold basedon a process known as dealloying. The

procedure involves treating a gold–silver
alloy with nitric acid that selectively removes silver, leaving behind a nanoporous
gold structure. Due to its remarkably
high specific surface area, nanoporous
gold is a material of emerging interest forthe development of novel catalytic andsensor applications.
Most fusion research projects at the
WPI-AIMR benefit from seed funding for
one year, and the institute is rare in its provision of financial funding for such shortprojects. “This type of financial support
allows younger researchers to concentrateon their projects without expending vast
amounts of time and energy applying for
research grants, thereby simplifying thewhole procedure,” says Hongwen Liu,an assistant professor in the Materials
Physics Group. Liu is currently developing plasmonic substrates that increase the

AIMResearch 2011

IN THE SPOTLIGHT

efficiency of opto-electrical conversion.
“I feel very fortunate to be working inan environment where the barriers that
normally exist between fields are broken
down, which allows younger researchers
like myself to work on truly cutting-edge
projects,” she says.
Fusion research enables researchers not
only to learn about new scientific developments outside of their respective fields,
but also to gain a fresh perspective on
their own work. “When I joined the WPIAIMR’s BMG Group after completing my
PhD in nanotechnology, I had to approach
metallic glasses from a physics point ofview,” says Koji Nakayama, an associate
professor of the BMG Group. Nakayama
conducts research on the controlled fabrication of metallic glass nanofibers basedon noble metals, which are characterized
by exceptionally high damage tolerance.
“In many ways, my time at the WPI-AIMR
from the very start has been one ongoing
fusion project,” he says.
The WPI-AIMR’s emphasis on maintaining open channels of communicationencourages researchers to learn from others and lend a helping hand to colleagues
and young researchers in particular.
Takeshi Fujita, an associate professor in
the BMG Group, notes, “A postgraduate

Researchers at WPI-AIMR’s ‘Tea Time’ event in August

AIMResearch 2011

student working on soft matter recently
asked me about using nanoporous gold asa cell substrate. I was happy to assist because manufacturing nanoporous gold is
my specialty.”
To facilitate the exchange of ideas
among its researchers, the WPI-AIMR
hosts seminars on a regular basis, andevery week holds a ‘Tea Time’ event designed to spark lively scientific discussion
in an informal setting. “These events not
only encourage us to learn about what
other people are doing, but also open our
minds to other research fields,” says Liu.
“If I ever go back to China, I would like tohold similar events for the benefit of mystudents and colleagues.”
Taking the green approachWith increasing demand for clean energy,
the WPI-AIMR is intensifying its focus ondeveloping innovative ‘green’ materials,
such as reusable catalysts, solar cells andsustainable engineering solutions basedon organic chemistry. Nakayama explains,“Green activities in Japan used to be concerned with how we can save the environment, but now they are more focused on
how renewable energy devices such as
solar cells with improved efficiency can be
developed through materials science.”

The recently opened WPI-AIMR Main Building

Advances in nanotechnology, forexample, are rapidly driving the development of next-generation charge-storage
devices that improve on the performanceof traditional lithium-ion batteries. Fujita,
who has been investigating the electrical storage capabilities of supercapacitors
using transition metal compounds, says,“We are aiming to develop a new type ofbattery that can be charged quickly using
solar cells and which in the future may becompatible for use in mobile phones andelectric cars.”
The WPI-AIMR’s commitment to developing new forms of green innovation
with a global outlook was reinforced bythe ‘Cutting-edge Functional Materials
for Green Innovation’ workshop held in
February 2011, which attracted many
internationally renowned materials scientists from the Asia-Pacific, Europe andNorth America.
By bridging the disciplines of materials
science, physics, chemistry, biotechnology and engineering, the WPI-AIMR not
only provides a unique environment that
nurtures the development of breakthroughtechnologies, but also continues to promote international joint research projects
and multidisciplinary exchange throughits satellite centers and network of 19 overseas collaborative research institutions.

25

IN THE SPOTLIGHT

INTERNATIONAL WORKSHOP

Published online 25 April 2011

Green innovation in the limelight
The 4th WPI-AIMR Annual Workshop was held in Sendai, Japan on 21–24 February 2011 drawing aninternational audience.

T

he WPI-AIMR Annual Workshop,
held on 21–24 February 2011
in Sendai, Japan, amid brilliant
late winter sunshine, is a central part ofacademic life at the WPI-AIMR, providing a forum for members of the instituteto meet as a body with other top-levelresearchers from around the world to discuss the state-of-the-art of materials science, establish research contacts and planfor the future.
In 2011, the workshop — the fourth
since the establishment of the WPI-AIMRat Tohoku University — was convenedat the Sendai International Center underthe banner of ‘Cutting-edge Functional
Materials for Green Innovation’, drawing more than 220 participants from 41
organizations in 10 countries, including
many senior and internationally renownedmaterials scientists from the Asia-Pacific,
Europe and North America.
Speaking to AIMResearch on the eveof the workshop, WPI-AIMR director
Yoshinori Yamamoto looked forward
to a lively and constructive meeting andoutlined his plans for the forward development of the institute, including the

Georg Bednorz

26further development of links with leadinginternational institutions such as the
University of Cambridge in the UK andadvancing the agenda of green innovation
at the WPI-AIMR. Yamamoto maintained
this theme in his welcoming address to
the workshop participants, recalling the
progress made by the institute’s researchers in further developing fusion researchand placing green innovation squarely at
the heart of the work of the institute.
“There is no doubt that creating new
functional materials for green innovation leading to the development of green
materials needs the approach of fusion
research,” he said. Following this, in his
opening remarks Tohoku University
president Akihisa Inoue congratulated
the WPI-AIMR on their “tremendous
efforts in advancing fusion research tocreate new research disciplines” andnoted the importance in this endeavorof the network developed between the
WPI-AIMR and its 22 partner institutions, which includes three satellite
centers located around the world. This
international outlook is manifestedby the large number of non-Japanese
researchers at the WPI-AIMR — justover half of the current total of 128 comefrom outside of Japan.
Inoue also spoke of his high expectations for the key part that the WPI-AIMR
will play in realizing his eponymous development plan for Tohoku University, which
he introduced in 2007. Describing the institute as a “locomotive for reinforcing the
research foundations of Tohoku University
as a research-intensive university,” Inouepraised the WPI-AIMR strategy of developing green innovation for the benefit ofsociety, calling the initiative “timely.” This

Sendai International Center

message was reinforced by Toshio Kuroki,
the WPI program director, in his welcoming address to the conference, calling upon
the WPI-AIMR to become “a frontrunnerfor materials science research by creating
new materials for a future society.”
Special lectures
Following the opening session, theacademic program of the conference
commenced with a special first session
composed of three lectures on a diverse
series of cutting-edge topics delivered bya trio of particularly highly acclaimed
materials science researchers. In thefirst of these, Georg Bednorz from IBM
Research Zürich, who shared the 1987
Nobel Prize in Physics, addressed theconference on the latest developments
in superconductivity. Bednorz notedthat 2011 is the 100th anniversary of the
discovery of the phenomenon of superconductivity, and went on to describe
recent developments in high-temperature
superconductivity, an area that has
witnessed a dramatic rise in importancein the last quarter century to the point

AIMResearch 2011

IN THE SPOTLIGHT

Peter Grünberg

that it has now become a key technology
for ensuring reliable, environmentallyfriendly and efficient energy use.
A neat counterpoint to the opening
lecture was given by the 2007 Physics
Nobel Laureate Peter Grünberg fromthe Jülich Research Centre in Germany,
who spoke on the use of giant magnetoresistance and its potential to address
problems of world energy. This was thesecond contribution made by Grünberg,
who had earlier entertained participants
as part of a musical ensemble that played

a selection of Japanese and Austrian folk
melodies at the pre-conference wine mixer
on the previous night. The special session
was rounded off by carbon nanotube
pioneer Sumio Iijima, Professor of Meijo
University as well as WPI-AIMR Adjunct
Professor, who reported on the current
state-of-the-art in the industrial production and applications of carbon nanotubes
and graphene. The theme of the closing
lecture was on one of the most pressing issues in materials science research and took
on even greater significance in the context
of the awarding of the 2010 Nobel Prize inPhysics for pioneering work in the field ofgraphene research.
Plenary lectures
The academic program also boasted 20
plenary lectures given by leading international materials scientists, including
memb ers of WPI-AIMR overs eas
satellite centers, as well as other presentations delivered in six parallel sessions. As in previous years, the lecture
program was supplemented by a poster

Sumio Iijima

session that drew over 80 contributions
on a wide variety of topics over the firsttwo days of the meeting. The researchpresented during the three days of the
4th WPI-AIMR Annual Workshop
encompassed a diverse range of topics
including bulk metallic glasses, materials physics, soft materials and device/system construction. In so doing it reflected the wide-ranging research remitof the center and further reinforced theworkshop as a key event in the annual
WPI-AIMR calendar.

FEATURED RESEARCHERS

Published online 25 July 2011

Fusion research abounds with
infinite possibilities
Recently appointed WPI-AIMR deputy director Motoko Kotani plans to use the power of mathematics to accelerate
fusion research between the institute’s various research groups.

In any walk of life, communication
matters, and science is no exception. So
when one of the leading experts in theworld in mathematics — a field that has thepower to generate closer communication
among scientists from different backgrounds — is brought in to enhance fusion
research, good things are bound to happen.
On 1 May 2011, Motoko Kotani, who
is a special advisor to Tohoku University
president Akihisa Inoue, officially started

AIMResearch 2011

her tenure as deputy director of the WPIAIMR. Kotani heads up the newly created Mathematics Unit and has been
charged with overseeing research carriedout at the WPI-AIMR. This will include
the important task of furthering fusion research between the four researchgroups that make up the institute: theBulk Metallic Glasses Group, Materials
Physics Group, Soft Materials Group andDevice/System Group.

Motoko Kotani27

IN THE SPOTLIGHT

An internationally renowned mathematician, Kotani received the prestigious Saruhashi Prize — given tofemale Japanese scientists for achieving
outstanding research results — in 2005
for her research on Discrete GeometricAnalysis on Crystal Lattices. When talking about mathematics, Kotani’s facebecomes animated and her voice takes ona strong, persuasive tone. “Mathematics
is appealing because it can break things
down to their very essence,” she says.
It is this strength that Kotani wants to
use to bring researchers from different
backgrounds together to work on crossdisciplinary research themes. This cansometimes be a challenge because theprincipal investigators in each researchgroup speak a distinctive scientific language that is not necessarily easy forothers to understand. “That is where wemathematicians come in. We can try tounderstand the background principles
between each scientific field, and thensimplify them to create a universal language that is understood by everybody,”
explains Kotani. “Simple ideas have theability to inspire others to develop theirown thoughts, which is how real fusion
research is conducted.”
Opening up communication
Communication is another key element
for promoting collaboration. Kotani plans
to have researchers in each group conduct
introductory seminars and survey talks
that give their colleagues a basic understanding of what their field of research isessentially about, rather than the kind ofpresentations where researchers simply
announce their latest findings. Without
such activities, Kotani believes that28

researchers will find it hard to bridge what
can be expansive scientific divides.
Kotani brings a wealth of international experience to her role and knows
the value of close-knit collaboration. In
1993–1994, she spent a year at the Max
Planck Institute in Germany, and in
2000–2001, she spent a year in Paris at
the prestigious Institut des Hautes Études
Scientifiques (IHÉS), an institute predominantly staffed by overseas researchers who mainly come from a mathematics
background, as well as some theoreticalphysicists and biologists. The spirit ofcooperation prevalent at the IHÉS allows
researchers to bounce ideas off eachother and make breakthroughs in theirresearch—something from which Kotani
herself benefited. “At the WPI-AIMR,
I would like to create an ideal research
environment similar to the one at IHÉS
where researchers can freely immersethemselves in their work,” says Kotani.
Supporting women in research
Another goal that Kotani feels passionately about is helping her fellow
female researchers. From 2006 to 2008,
she was the project leader in the Tohoku
Women’s Hurdling Project — an initiative
established by the Japanese government
to ‘develop models that support women
researchers’. The establishment of sucha program is very much in keepingwith the strong tradition of promoting
female involvement in science at Tohoku
University, which in 1913 was the first
university in Japan to admit women as
undergraduate students.

Today, the university provides researchers with family assistance, including kindergarten and babysitting services. Suchfacilities are particularly important for female researchers from overseas, who maylack the ability to communicate effectively
in Japanese and thus find help on theirown. Kotani says she will do her utmost
to create a system that allows female researchers to concentrate on their research
but also spend time with their family —essential for allowing them to relax andformulate ‘wild’ ideas. “If you have toworry about your family, you cannot concentrate on your research,” she notes.
Establishing an environment in whichfemale researchers find it pleasant towork is also crucial. “If you create an atmosphere that is comfortable for female
scientists, it is comfortable for everybody,”
says Kotani, who is eager to stress that her
goal, and that of the university as a whole,
is to make the university a top-notch research university that is attractive to men
and women alike.
Such ambitions extend not just to researchers from inside Japan but also to
those from other countries. Kotani is quick
to point out that the WPI-AIMR has muchto offer researchers from overseas, including a wealth of opportunities to interact
with preeminent scientists from a wide
spectrum of disciplines, creating an environment where stimulating ideas are often
exchanged. The possibilities for fusion
research at the WPI-AIMR, Kotani notes,
are practically endless. “We want researchers to think of one and one as not being
equal to two — but to infinity,” she says.

AIMResearch 2011

The new WPI-AIMR Main Building incorporates a part of theoriginal building which formerly housed the Departmentof Metallurgy in the School of Engineering. It promotes
collaborative research by bringing together researchers
from materials science, physics, chemistry, biotechnology,
engineering, and mathematics under one roof.

Advanced Institute for Materials Research
Tohoku University

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