International Workshop on Computational Science 2017
February 15–18, 2017
Kanazawa University, Japan
Date February 15–16, 2017 (Main Session)
February 17–18, 2017 (Special Session)
Venue Kanazawa University, Japan (Kakuma campus)
Kakuma-machi, Kanazawa 920-1192
Lecture hall: 203, main building of Graduate school of natural science andtechnology, building S1.
http://www.kanazawa-u.ac.jp/e/campuses/
URL http://polaris.s.kanazawa-u.ac.jp/iwcs2017/
This workshop is supported by Kanazawa University SAKIGAKE Project.
The special session of IWCS2017: “Design of Novel Magnetic Materials for Device Applications:
Simulation and Experiment” is co-organized by Post-K Priority Issue 7 - Creation of new functional devices and high-performance materials to support next-generation industries (“CDMSI”)

Program of the Main Session
February 15
13:30 – 13:40

Opening

Invited lectures (25min + 5min Q&A)
13:40 – 14:10

Edy Tri Baskoro (Institut Teknologi Bandung)Ramsey number for graphs

14:10 – 14:40

Mirza Satriawan (Universitas Gadjah Mada)
Multicomponent Dark Matter in the Mirror Model with Massive Mirror Photon

14:40 – 15:10

Jiraphan Suntornchost (Chulalongkorn University)
Variable selection for a regression model when dependent variable is subject tomeasurement errors

15:10 – 15:40

Kazutomo Kawaguchi (Kanazawa University)
Theoretical Study of Intermolecular Interactions for protein systems
1

15:40 – 16:00

Break

16:00 – 17:00

Short presentations (3min)

17:00 – 18:00

Poster session (room 202)

February 16
Invited lectures (25min + 5min Q&A)
09:30 – 10:00

Acep Purqon (Institut Teknologi Bandung)
Urban Physics and Its Implementation in Predicting Economic Growth Related
to High Speed Train Development

10:00 – 10:30

Manabu Oura (Kanazawa University)
Ring of the weight enumerators of dn+

10:30 – 11:00

Fatimah A. Noor (Institut Teknologi Bandung)
Modeling of Tunneling Current in High-k-based MOS Capacitors by Considering the Effects of Coupling between Longitudinal and Transverse Motions

11:00 – 11:20

Break

11:20 – 11:50

Suprijadi (Institut Teknologi Bandung)Experimental and Computational study on physical properties based on granular system

11:50 – 12:20

Triati Dewi Kencana Wungu (Institut Teknologi Bandung)
Natural Clay Mineral as Adsorbent for Health and Environment Applications:A Density Functional Theory Study

12:20 – 12:50

Tatsuki Oda (Kanazawa University)
Research and development of high performance material for voltage torque
MRAM by means of first-principles calculation

12:50 – 13:00

Closing

2

Program of the Special Session“Design of Novel Magnetic Materials for Device Applications:
Simulation and Experiment”
February 17
9:30 – 9:35

Opening

9:35 – 10:15

Y. Sakuraba (NIMS)
Exploration of ferromagnets with large anomalous Nernst effect for novel thermoelectric applications

10:15 – 10:40

Y. P. Mizuta (Kanazawa Univ.)
Skyrmion-driven thermoelectric conversion: An ab intio study

10:40 – 11:00

Break

11:00 – 1:40

T. Koretsune (RIKEN)First-principles calculation of Dzyaloshinskii-Moriya interaction

11:40 – 12:05

M. Ohashi (Kanazawa Univ.)
Superconductivity of chromium thin film

12:05 – 13:35

Lunch

13:35 – 14:15

A. Kawasuso (QST)
Application of spin-polarized positron spectroscopy to some ferromagnetic systems

14:15 – 14:55

K. Hyodo (JST-CREST, Tohoku Univ.)
First-principles study on intrinsic and extrinsic anomalous Hall conductivity oftransition metal alloys

14:55 – 15:20

Break

15:20 – 16:00

A. Edström (ETH Zürich)Computational Design of Transition Metal Magnets with Large Magnetocrystalline Anisotropy

16:00 – 16:40

T. Nozaki (Tohoku Univ.)
Voltage control of magnetization using magnetoelectric antiferromagnet Cr2 O3
sputtered thin film

16:40 – 17:05

M. Obata (Kanazawa Univ.)
Investigation of spin dependent van der Waals density functional approach

17:45 –

Banquet (for special session participants, Sumire-Tei in Kanazawa university)3February 18
9:10 – 9:50

K. Ohishi (CROSS)
Chiral magnetism in CsCuCl3 probed by polarized neutron scattering and muon
spin rotation

9:50 – 10:30

H. Nakanishi (NIT, Akashi College)
Quantum simulation for the motion of positive-muon in materials and its application for Mu-SR spin state analysis

10:30 – 10:55

J. B. Lin (NIMS)
Linear-scaling DFT study on the structural optimization and electronic properties of real size Ge/Si core-shell nanowires

10:55 – 11:15

Break

11:15 – 11:55

Y. Onose (Univ.Tokyo)
Nonreciprocal propagation of elementary excitations in noncentrosymmetricmagnets

11:55 – 12:35

Y. Ohnuma (JAEA)
Theory of spin current generation

12:35 – 12:40

Closing4

List of posters
1. Yoshiho Akagawa (Kanazawa University)
Numerical simulation for dynamical elastic contact problem
2. Saeful Akhyar (Kanazawa University)
Smoothed particle hydrodynamic simulation of accretion disk in cataclysmic variable
3. Hasan Al Rasyid (Kanazawa University)
First-Principles Study of Electronic, Magnetic, and Optical Properties of Nickel Cobaltite:
DFT and QSGW methods
4. Fadil Habibi Danufane (Kanazawa University)
Holonomic Gradient Method for the Distribution Function of the Largest Root of Complex
Non-Central Wishart
5. Yosuke Funato (Kanazawa University)
First-principles study on θ-phase in solid oxygen
6. Kouta Futai (Kanazawa University)
Numerical study of an adaptive Lagrange-Galerkin scheme for pure convection problems
7. Nurul Ikhsan (Kanazawa University)
Theoretical study on multi-functional Fe/MgO interface: investigation of perpendicular magnetic anisotropy origin
8. Tomosato Kanagawa (Kanazawa University)
First principles calculation of magnetic anisotropy energy on double interfaces slab systemsof X/Fe/MgO
9. Hiroyuki Kitano (Kanazawa University)
Numerical simulation of contact problem of an elastic body with friction
10. Susumu Minami (Kanazawa University)
Hyperfine structure of muonium in GaN
11. Masum Murshed (Kanazawa University + University of Rajshahi, Bangladesh)On the prediction of storm surge along the coast of Bangladesh
12. Takumi Nakano (Kanazawa University)
3D simulation of crack propagation in an elastic body by a phase field model
13. Irma Palupi (Kanazawa University)
An Implicit Boundary Integral Method for Laplace Problem
14. Riska Wahyu Romadhonia (Kanazawa University)
Finite elements method of ergodic distribution function for Jaffe model
15. Ayu Shabrina (Kanazawa University)
Numerical method of nonlinear Black Scholes equation for American options pricing
516. Shogen Shioda (Kanazawa University)
Computation of an inverse free boundary problem for a shape optimization method
17. Hiroki Yamamoto (Kanazawa University)
A gradient flow structure of the Maxwell-type viscoelastic model and its finite element analysis
18. Yamaoka Ryohei (Kanazawa University)
4 way-hexagonal symmetric crystalline method and 2 dimensional snow crystal model allowing collision / splitting
19. Takuro Yoneda (Kanazawa University)
Development of a finite element method for a delamination model and its simulation
20. Yang Zhenxing (Kanazawa University)
Minimum energy state and gradient flow for interaction energy of particles

6

RAMSEY NUMBER FOR GRAPHS
Edy Tri Baskoro
Combinatorial Mathematics Research Group
Faculty of Mathematics and Natural Sciences
Institut Teknologi Bandung (ITB)
Jalan Ganesa 10 Bandung, Indonesia
Email: ebaskoro@math.itb.ac.id
Abstract. Ramsey theory first appeared in the context of propositional logic(1928). This theory became famous after Paul Erdos and George Szekeres (1935)
applied it in graph theory. Determining the exact values of the classical Ramsey
numbers R(m; n) has received a lot of attention. However, the results are still far
from satisfactory. On the other hand, graph Ramsey theory as one of its
generalizations has grown enormously in the last four decades to becomepresently one of the most active areas in Ramsey theory. For any graphs G and H,
the Ramsey number R(G,H) is denoted as the least integer t such that any red
blue coloring on the edges of the complete graph on t vertices yields either a red
G or a blue H as a subgraph. The Ramsey number R(G,H) has been studied forvarious pairs of G and H. In this talk, we shall give a survey on the finding ofRamsey numbers R(G,H) if one of G and H is a wheel. We also discuss the Ramsey
numbers R(G,H) if either G or H is a union of graphs.

Multicomponent Dark Matterin the Mirror Model with Massive Mirror Photon
Mirza Satriawan
Department of Physics, Universitas Gadjah Mada,
Bulaksumur BLS 21 Yogyakarta 55281, Indonesia
mirza@ugm.ac.id
A modified mirror model, whose gauge group is SU(3)1 ⊗SU(3)2 ⊗SU(2)L ⊗SU(2)R ⊗U(1)Y 1 ⊗U(1)Y 2
and the particles content consist of the ordinary SM particles (plus the right handed neutrinos)
and their parity mirror partners, can provide a multicomponent dark matter sector, consist of cold
and warm dark matter components. I add to the original mirror model a singlet scalar φe andits mirror partner φE , whose quantum numbers are the same as the singlet right handed electron
and its mirror-partner. The φE can have a non zero VEV, while the φe remains with zero VEV.
As consequences: Mirror photon will obtain mass whose order is around the neutral weak boson
mass, rendering the mirror electromagnetic-like interaction to be weak; The φe will decay slowly
producing more entropy in the ordinary sector, providing an escape to the BBN constraint for thismodel; There is a mixing among the ordinary and mirror neutrinos, and the singlet and doublet
mirror electrons, as a result the mirror doublet electron have masses in the keV order, becoming
the warm dark matter component of this model.
The asymmetric part of mirror baryons have energy density at the same order as ΩB , and since
the mirror electromagnetic-like interaction is weak, the mirror baryons can condense and becomea very large mirror atomic-nucleus, becoming the cold dark matter component of the model. The
symmetric part of mirror electrons cannot annihilate into mirror photons, and its abundance iscomparable to the ordinary photons but suppressed by the temperature different of the two sectors.
Since their mass is in the keV order, they can contribute an energy density in the same order as ΩB .
PACS numbers: 12.60.-i, 11.30.Er, 95.35.+dVariable selection for a regression model when
dependent variable is subject to measurement
errors∗Partha Lahiri and Jiraphan Suntornchost†

Abstract
In this paper, we ﬁrst examine the accuracy of a given variable selection criterion (e.g., adjusted R2 ) for a regression model when dependent variable is subject tomeasurement error variability. Such a situation occurs, for example, in small area estimation where one explores the relationship between the true small area mean and aset of known auxiliary variables. We show that the approximation error, that is, thediﬀerence between the standard variable selection criterion and the corresponding ideal
variable selection criterion without any measurement error variability, does not converge
to zero even for a large sample size. In our simulation, we notice that standard variableselection criterion could severely underestimate the ideal variable selection criterion inpresence of high measurement error variability. We device a simple adjustment to thestandard variable selection criterion that reduces the approximation errors considerably.
In particular, we show that the approximation error for our new variable selection criterion converges to zero for large sample size. We demonstrate through simulation thatour proposed variable selection criterion tracks the ideal variable selection criterion very
well compared to the standard variable selection criterion.
Key Words: Adjusted R2 ; small area estimation.

∗

The research was supported in part by National Science Foundation grant SES-0851001 and a National

Institute of Health subcontract from the University of Michigan.
†
Presenter

1

Theoretical Study of Intermolecular Interactions for protein systems
Kazutomo Kawaguchi, Satoshi Nakagawa and Hidemi Nagao
Institute of Science and Engineering, Kanazawa University, Kanazawa, Japankkawa@wriron1.s.kanazawa-u.ac.jp

Association of protein molecules plays a key role in many protein functions,
such

as

signaltransduction,transcription,

andelectrontransportinphotosynthesis. We have discussed the association of protein molecules by usingcoarse grained model in which protein-protein interaction is represented by only
van der Waals interaction [1]. We have also investigated that the effective
attraction interacts between a protein molecule and its ligand molecule in a water
solvent by using all-atom molecular dynamics (AAMD) simulations [2].
In this study, we construct the coarse grained model to represent theeffective interaction between protein molecules in a water solvent. The effective
interaction between two amino acid side chains in a water solvent is calculated asa function of the distance between them by using AAMD simulations. The coarse
grained potential function for each amino acid side chain is constructed torepresent the effective interaction obtained by the AAMD simulations. We show
that

the

Langevin

dynamics

simulation

with

Gō-like

model

and

our

coarse-grained model reproduces a homotetramer complex structure of GCN4-pLI
and that the interactions between hydrophobic amino acid residues promote theassociation of GCN-pLI monomers [3].

[1] M. Rusmerryani, M. Takasu, K. Kawaguchi, H. Saito, H. Nagao, JPS Conf. Proc., 1(2014) 012054.
[2] K. Kawaguchi, H. Saito, S. Okazaki, H. Nagao, Chem. Phys. Lett., 588 (2013) 226-230.
[3] K. Kawaguchi, S. Nakagawa, S. Kinoshita, M. Wada, H. Saito, H. Nagao, Mol. Phys.
(2016) in print.

Urban Physics and Its Implementation in Predicting
Economic Growth Related to High Speed Train Development
Acep Purqon, Sparisoma Viridi
Physics of Earth and Complex Systems, Institute of Technology Bandung, Indonesia
Email: acep@fi.itb.ac.id
Abstract. Contribution to complexity in urban problems and its challenges can be provided
nowadays using urban physics, a well-established discipline, incorporating relevant branchesof physics, environmental chemistry, aerodynamics, meteorology and statistics. Growth ofcities and their connections are complex and very similar to organic systems in biology.
Interventions in the terms of policy, that borrow principle from theoretical physics, could help
to improve urban planning (Pollock, 2016). Pedestrian wind comfort, pedestrian thermal
comfort, building energy demand, pollutant dispersion and wind-driven rain are five eminent
problems in the field of urban physics, closely linked to urbanisation (Moonen et al., 2012).
Using networks in analyzing available big data, e.g. urbanisation, economic growth, educationlevel, population quality, etc., and correlating them might produce some interesting phenomena
such as small world effect (Newman, 2008). Development of high seed train Jakarta-Bandungand related analysis to growth of cities along the paths is a hot current topic, since it requiresby the government, especially the local ones, in supporting their strategy and policy to control
the organic development of economics, which could trigger over population, social problem,and even crime rate, besides increasing the local income and speeding up land opening. It
might potentially result in excessive resource utilization in the Jakarta Bandung region(Firman, 2009). In this talk influence of policy are discussed, how it can change utilization ofregion and cities passed by the train path.
References
1. Firman T 2009 Habitat Int. 33 327
2. Newman M 2008 Phys. Today 61 33
3. Moonen P, Defraeye T, Dorer V, Blocken B and Carmeliet J 2012 Front. Arch. Res. 1 197
4. Pollock K 2016 Nature 531 S64

Ring of the weight enumerators of d+n
Makoto Fujii

Manabu Oura

Kanazawa University
makotofkanazawa@gmail.com

oura@se.kanazawa-u.ac.jp

First we recall the connection among algebraic combinatorics, the invariant theory of thefinite groups and the theory of modular forms. And then, we take up a special Type II code+d+n . It is shown that the ring over C generated by the weight enumerators of dn is finitely

generated over C. Moreover, we can give enough elements to generate the ring. This result is
applied to determine a set of generators of the ring for small genus.

1Modeling of Tunneling Current in High-k-based
MOS Capacitors by Considering the Effects of
Coupling between Longitudinal and Transverse
Motions
Fatimah A. Noor*, Mikrajuddin Abdullah, Khairurrijal
Physics of Electronic Materials Research Division
Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung
Jalan Ganesa 10, Bandung 40132, Indonesia*Email: fatimah@fi.itb.ac.id

Since sixty years ago, many theoretical and experimental investigations have been done to study
electron tunneling processes in heterostructures. As one type of heterostructures, silicon-based
metal-oxide-semiconductor field effect transistors (MOSFETs) are the base of modern computers
and telecommunications, and the drudge of the integrated circuit technology. Because of
emerging applications involving lower voltage operation, higher speed and density, MOSFETs
are aggressively scaled down to the sub-micrometer regime and below and consequently theshrinking of the SiO2 gate-dielectric thickness down to sub-nm region. Huge tunneling current
occurs and power dissipation becomes significantly high when the SiO2 gate-dielectric thickness
is less than 1.5 nm. High dielectric constant (k) materials are the most potential dielectrics tosubstitute SiO2. A gate oxide demanded to replace SiO2 is a stack of SiO2 and a high-k layer
known as a high-k dielectric stack because an ultra thin interfacial SiO2 often forms during the
fabrication process. Several models have been proposed to calculate the tunneling current inhigh-k -based MOS capacitors. However, they did not consider a coupling effect between
transverse and longitudinal energies and anisotropic masses. On the other hand, it is well known
that an electron does not move in the longitudinal direction only but also in the transverse one. In
this research, we develop a model of tunneling current in high-k -based MOS capacitors bytaking into account the coupling effect of transverse-longitudinal motion and anisotropic masses.
The calculated tunneling current is then compared to the measured one to examine the accuracyof the model.

Experimental and Computational study on physical properties based on granular system
H.Setiadi1, A. Ikhsan1, T.D.K. Wungu2, S. Viridi2 and Suprijadi2
1

Department of Computational Sciences, 2Department of Physics
Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung,
Jl. Ganesha No.10, Bandung 40132, INDONESIA
Abstract
In recent years, research on granular system computation increase significant in department of
Physics ITB. The computation in many fields were applied with different methods such assmoothed particle hydrodynamics (SPH), moving particle semi-implicit (MPS), molecular
dynamics (MD) and other standard methods. The other hand, to clarify the results, we did someexperiments to refine the model. In this presentation, we will present experimental andcomputational study on fluid drop, Brazil-nuts effect phenomenon, and two dimensional (2D)
material under uniaxial force.
We do simple experiment on fluid drop under on a filter like sheet to clarify the result on effect ofparticle size fluid drop and the possibility to separate two different fluids base on particle size.
Research on Brazil-nut effect was begun more than 30 years ago, but still interesting because of theapplication of this phenomena can be implemented in many different area. The simple experimentand simulation based on granular system shows us the influence of frequency and amplitude. In the
2D material the model were based on experiment on thin rubber under uniaxial forces and atomic
bond model, the results shows good relation between forces and elongation of rubber. Based on thisresults, we applied to silicine with its parameter and behavior for studying morphology changing
during stressed under controlled forces. Also we studied on the the effect of morphology change toelectronics properties of silicine using DFT by VASP.
Keywords :granular, sph, mps, md, electronic behaviour

Natural Clay Mineral as Adsorbent for Health and Environment Applications:A Density Functional Theory Study

Triati Dewi Kencana Wungu, Widayani, and Suprijadi

Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung,
Jl. Ganesa 10 Bandung 40132, Indonesia
E-mail: triati@fi.itb.ac.id

Abstract

In this study, we present application of natural clay mineral, that is montmorillonite, using firstprinciple-calculations by means of electronic structure calculation with emphasis on approaches
based on Density Functional Theory (DFT). A montmorillonite has a large surface area whichbrings beneficial to adsorb any atoms or molecules to its surface. Therefore, montmorillonite canacts as a good adsorbent material and hence can be used for a wide variety of environmental andhealth applications. Here, the mechanism of atom/molecule adsorption on the surface ofMontmorillonite is investigated to seek their interaction in an atomic scale point of view. The
atoms such as Pd and Cs are used in this simulation to obtain the results of their interaction with
Ca-montmorillonite. For the calculation method, we used DFT within Kohn-Sham formula
implemented in Vienna Ab initio Simulation Packages (VASP). The generalized gradientapproximation (GGA) within the Perdew–Burke–Ernzerhof (PBE) functional was employed for theexchange-correlation energy. The Brillouin zone was sampled using 5 x 5 x 1 Monkhorst-Packk-point grid and the cut off energy is 520 eV. The total energies are converged to 0.01 meV.

Keywords:

DFT, montmorillonite, Pd, Cs

Research and development of high performance material forvoltage torque MRAM by means of first-principles calculation
Tatsuki Oda
Institute of Science and Engineering, Kanazawa University, Kakuma-machi,
Kanazawa 920-1192, Japan, *E-mail: oda@cphys.s.kanazawa-u.ac.jp

Since the electric-field (EF) control of ferromagnetism was discussed in 2000 [1], thestudy on EF effect in the thin magnetic film has been performed very actively. After theinterface of Fe/MgO was proposed [2], much effort has been devoted in order to realizea spintronic device application. A proto-type of voltage torque magnetic random accessmemory (MRAM) was proposed as an ultra-low-power high-speed memory [3]. Its
technique contains new voltage-controlled writing method for nonvolatile solid-statemagnetic memory. Such memory is considered to have a potential for replacing the rolesof conventional SRAM and DRAM. To build a spintronic device for widely used memory,
various kinds of development are requested. Such development will be achieved in a partof the ImPACT (Impulsing PAradigm Change through disruptive Technologies Program)project, organized by CAO(Cabinet Office, government of Japan), managed by Masashi
Sahashi in Tohoku University, and sponsored by JST(Japan Science and Technology
agency). Kanazawa University (main researcher is Tatsuki Oda) has been contributed tothe project since April in 2016 from the side of computational science.
In the project, Kanazawa group has studied both the analysis of mechanism and thematerial design for high performance interface magnetic anisotropy and voltage control.
With using first-principles computations based on the density functional theory, we haveinvestigated the electronic, atomic, and magnetic structures in the Fe/MgO interface andits family. Our approach employs the spin-orbit interaction which comes from therelativistic effect of electrons around atom nucleus, being enable to estimate the magnetic
anisotropy energy (MAE) and the EF effect (EFE) imposed on the interface. In our
simulation, the lattice constant in interface plane, the materials of ferromagnet andinsulator, and the coordinates of atoms are treated as input parameters. Though both theanalysis and simulation, the conditions for high performance system is desirable. I
introduce the project and explain the approach based on computational science in the talk.
This work was supported by the ImPACT Program of Council for Science, Technology andInnovation (Cabinet Office, Japan Government) and by the Kanazawa University SAKIGAKE
Project.

[1] H. Ohno et al., Nature 408, 944 (2000); Nat. Mater. 9, 952 (2010).
[2] T. Maruyama et al., Nat. Nanotech. 4, 158 (2009).
[3] Y. Shiota et al., Nat Mat. 11, 39 (2012).

Special Session of IWCS2017: ”Design of Novel Magnetic Materials for Device Applications: Simulation and Experiment

17a-1

Exploration of ferromagnets having large anomalous
Nernst effect for novel thermoelectric applications
Yuya Sakuraba, Taisuke Sasaki, Seiji Mitani, and Kazuhiro Hono
1

National Institute for Materials Science, Tsukuba, Japanemail: sakuraba.yuya@nims.go.jp

SANE (uV/K)

Anomalous Nernst effect (ANE) is a thermoelectric phenomenon that generates an electric
voltage to the cross product direction between the magnetization and the temperature gradientin a ferromagnetic material. Previously, Sakuraba et al. proposed that there are advantages toapply ANE for thermoelectric applications owing to its three dimensionality in contrast to one
dimensionality of conventional Seebeck effect, e.g. the electric voltage can be easily
increased by making a simple laterally connected structure etc. (Fig.1) [1,2]. However, toimprove thermoelectric power originating from ANE (SANE) is necessary to make practicalapplications more realistic. Since anomalous/spin Hall effect (AHE, SHE) and ANE are
related phenomena, we can learn how to enhance ANE from previous studies on AHE and
SHE. Niimi et al reported that the spin-Hall angle in Cu can be drastically enhanced by heavy
elements Ir and Bi-doping.[3,4] Therefore, in this study, we have investigated the effect ofheavy elements (Ta, Ir, Bi) doping to Fe film for an enhancement of ANE effect.
The heavy elements doped Fe films were deposited by a co-sputtering method using pure Fe
and Ta/Ir/Bi targets on MgO substrates. ANE effect was measured by applying temperature
gradient and external magnetic field to the in-plane and out-of-plane directions of the films,
respectively.
It was found that AHE and ANE in Fe films were drastically enhanced by doping Ir. The Fe
film with 16-18 at.% Ir shows about 4 times larger thermopower SANE and one order ofmagnitude larger ANE angle θANE (defined in SANE/SSE here) than those in pure Fe film
(Fig.2). Observed θANE of 38% is the highest ever reported in any ferromagnetic materials
such as FePt (θANE ~ 15%). Although SANE is still rather small due to small SSE of Fe and themechanism of the enhancement of SANE has not been clarified yet, the enlargement of θANE byheavy element doping is SANE for further improvement of thermopower of ANE.
[1]Sakuraba et al., APEX 6, 033003 (2013), [2]Y. Sakuraba, Scripta Materialia 111, 29-32(2016)., [3]Y. Niimi et al., Phys. Rev. Lett. 109,
0.5
1566
0.4
0.3
0.2
0.1
0.0

θANE (%)

40
30
20
10
0
0

Figure 1: Example of thermoelectric power
generation based on ANE using a tube shapeheat source.[2]

5

10

15

20

25

30

Ir composition (at.%)Figure 2: Ir composition dependence ofthermopower of ANE (SANE) andanomalous Nernst angle (θANE) in Irdoped Fe films.

Special Session of IWCS2017: ”Design of Novel Magnetic Materials for Device Applications: Simulation and Experiment

17a-2

Skyrmion-driven thermoelectric conversion:
An ab intio study
Yo Pierre Mizuta1, Hikaru Sawahata1 and Fumiyuki Ishii2
1

Graduate School of Natural Science and Technology, Kanazawa University
2

Faculty of Mathematics and Physics, Kanazawa University
email: mizuta@cphys.s.kanazawa-u.ac.jp

The magnetic skyrmion, a topological object formed by spins in condensed matter, exhibits many peculiar
properties, among which we target the anomalous Nernst effect (ANE), heat-to-electricity conversion intransverse direction, driven by an emergent magnetic field B originating from its spin texture. We have foundthrough ab initio calculations on a single s-orbital model using the codes OpenMX [1] and Wannier90 [2] that,in the skyrmion crystal (SkX) phase (Fig.1), where skyrmions are crystallized in two dimensions, thecrystal-momentum component of B generates large ANE when chemical potential µ is properly tuned (Fig.2)[3]. This was found to be due to rapid variation of Chern numbers with respect to energy in the band structure,
which had been implied in an earlier tight-binding model analysis [4] and further studied ab initio [5].
Following such an observation in the simplest model of square SkX [3], our subsequent computations on more
realistic models of transition-metal oxides also have predicted possible large ANE.
This motivates further studies in quest of better thermoelectric materials that exploit this effect.

T=300K

Left: Fig. 1. An example of Skyrmion crystal-1.6µ (eV)

Right: Fig. 2. Large ANE coefficient (blue) in a SkX (s-orbital model of Ref. [3])[1] T. Ozaki et al., http://www.openmx-square.org.
[2] A.A. Mostofi et al., http://www.wannier.org.
[3] Y. P. Mizuta and F. Ishii, Scientific Reports 6, 28076 (2016).
[4] K. Hamamoto, M. Ezawa and N. Nagaosa, Phys. Rev. B 92, 115417 (2015).
[5] H. Sawahata, Y. P. Mizuta and F. Ishii, International Workshop on nano-spin conversion science &quantum spin dynamics, Poster Q-22, Oct.14, 2016, Tokyo.

0.0

Special Session of IWCS2017: ”Design of Novel Magnetic Materials for Device Applications: Simulation and Experiment

17a-3

First-principles calculation of Dzyaloshinskii-Moriya
interaction
Takashi Koretsune
RIKEN CEMS, Saitama, Japanemail: takashi.koretsune@riken.jp
In noncentrosymmetric magnetic systems, the spin-orbit coupling induces an antisymmetricexchange interaction between spins, called Dzyaloshinskii-Moriya (DM) interaction. This
interaction favors twisted magnetic structures unlike the usual symmetric interactions. Thus,
controlling this unique interaction opens a new possibility of engineering magnetic behavior.
Here, we show two approaches to evaluate the DM interaction from first principles. One canbe regarded as a perturbation with respect to the exchange couplings and the DM interaction
is expressed by the off-diagonal spin susceptibility[1]. The other can be obtained byexpanding the effective Hamiltonian with respect to the spatial derivative of local spins andthe DM interaction is given by the intrinsic spin current[2]. Using these two approaches, we
calculate the DM interaction for Mn1-xFexGe, which is a typical skyrmion host material, andshow how our methods explain the experiments.
This work was done in collaboration with R. Arita, N. Nagaosa, G. Tatara and T. Kikuchi.
[1] T. Koretsune, N. Nagaosa, and R. Arita, Sci. Rep. 5 13302 (2015).
[2] T. Kikuchi, T. Koretsune, R. Arita, and G. Tatara, Phys. Rev. Lett. 116 247201 (2016).

Special Session of IWCS2017: ”Design of Novel Magnetic Materials for Device Applications: Simulation and Experiment

17a-4

Superconductivity of chromium thin film
Masashi Ohashi1,2, Masaki Sawabu2, Kohei Ohashi2, Masahiro Miyakawa2,
Takahide Kubota3, Koki Takanashi3
1

Institute of Science and Engineering, Kanazawa University, Kanazawa, Japan
2
Graduate School of Natural Science and Technology, Kanazawa University,
Kanazawa, Japan
3
Institute for Materials Research, Tohoku University, Sendai, Japanemail: ohashi@se.kanazawa-u.ac.jp

From the point of view not only of pure research but also of applied and practical one, there
are many examples of superconducting thin films. But almost all of them were those inwhich superconductivity disappears when the film thickness is made thin [1]. It is likely tomake a superconducting electron pair when it becomes thinner than the mean free path ofelectrons.
On the other hand, Schmidt et al. reported that thin films of chromium (Cr) metal suppress
the antiferromagnetic ordering and become superconductive at TC∼ 1.5 K [2]. Taking accountthat the bulk Cr is an antiferromagnet below TN = 311 K and does not show superconductivity[3], the relationship between film thickness and existence of superconductivity of Cr is
opposite to the other examples of superconducting thin films.
Assuming that the magnetic correlation interaction is suppressed by controlling the film
thickness, Cr may show a magnetic order-disorder transition tuned by the film thickness,and unconventional superconductivity may occur at the quantum critical point of T →0,
where an electron pair appears due to quantum fluctuation. Generally, the three-dimensional
electron system such as bulk compounds and two-dimensional one such as thin films aredescribed by completely different Hamiltonian. That is, film thickness is an effective
parameter that can directly control dimensionality, and it is interested in whether Cr is thefirst case of the new quantum phase transition tuned by film thickness [4]. In the present
study, we perform precise electrical resistance measurements of chromium thin films toclarify the electronic state in a wide temperature range.
[1] H. M. Jaeger, D. B. Haviland, B. G. Orr, A. M. Goldman, Phys. Rev. B, 40 (1989) 182.
[2] P. H. Schmidt, R. N. Castellano, H. Barz, B. T. Matthias, Physics Letters, 41A (1972) 367.
[3] M. Ohashi, G. Oomi, Jpn. J. Appl. Phys., 48 (2009) 070221.
[4] M. Ohashi, K. Ohashi, M. Sawabu, M. Miyagawa, T. Kubota, K. Takanashi, Physics
Letters A, 380 (2016) 3133.

Special Session of IWCS2017: ”Design of Novel Magnetic Materials for Device Applications: Simulation and Experiment

17p-1

Application of spin-polarized positron spectroscopy
to some ferromagnetic systems
A. Kawasuso
National Institutes for Quantum and Radiological Science and Technology (QST), 1233,
Watanuki, Takasaki, Gunma 370-1292, JAPANSpin-polarized positron spectroscopy may be a unique tool for studying
spin-polarized electronic states. That is, this method is applicable to the investigations of (i)spin-polarized electron momentum distribution (SP-EMD) of bulk system which connectswith the band structure, (ii) magnetic moments associated with vacancy defects that cause
so-called d0 ferromagnetism of semiconductors, and (iii) surface spin-polarization offerromagnets and also strong spin-orbit coupling systems. In this talk, I introduce recent
results on SP-EMDs of Heusler alloys (Co2Mn(Fe)Si(Al), NiMnSb), spin-polarizations of
vacancies in ZnO and GaN, and spin injection from Co to single layer graphene and BN.
Open circles in Fig. 1 shows the SP-EMDs measured for Co2MnSi and Co2MnAl
polycrystals. The SP-EMD of Co2MnSi is composed of a low momentum peak around pz=0
m0c and a high momentum shoulder around pz=10x10-3 m0c. Contrary, the intensity of the
SP-EMD of Co2MnAl is significantly lost around pz=0 m0c. The measured SP-EMDs are ingood agreement with a package code (ABINIT) band structure calculation. This first suggeststhat the calculation was done with enough precision. The peak of the SP-EMD of Co2MnSi at
pz=0 m0c is explained as the existence of sp-like band dispersion of majority spin bands near
the Fermi level. Whereas, the valley of the SP-EMD of Co2MnAl at pz=0 m0c is explained as
the absence of such bands.
Band 1
Band 2
Band 3
Band 4
Band 5
Band 6
Band 7
Band 8Band 9Band 10

Co2MnSi

7

0.00

9

12

4 10 11

17

1

18

13-16

19

82

15
19

19

10

5

17
16
15
14

18

EF

17

18

16
15
14
12 13
11
10 9
8
7
6
5
4

13
12
9
6

5

11
7 8

10

4
3

3
2

5
6
3

Co2MnSi

1

1

Minority spin

Majority spinBand 1
Band 2
Band 3
Band 4
Band 5
Band 6
Band 7
Band 8Band 9

Co2MnAl

0.01

13-16
9

1 8

0.00

6

4
2

7

17
12
11
10

Band 10
Band 11
Band 12Band 13Band 14
Band 15
Band 16
Band 17
Total
Exp.

0
W
15

L

16

10

15

14

6

8
6
5

7
5
4

5

20

25

Electron momentum, pz (x10-3 m0c)

10

2

1

W

9
7

3

2

15

X

4

3

10

G

16
15
14
13

12
11

13
12
11
10
9
8

5

5

L

EF

17

3

0

XW

G

17

Energy (eV)

Nmaj(pz) - Nmin(pz)0.01Band 11
Band 12Band 13Band 14
Band 15
Band 16
Band 17
Band 18
Band 19
Total
Exp.

Energy (eV)0.02

Majority spin
LG

Co2MnAl1

XW

Minority spin
L

G

X

Figure 1 Spin-polarized electron momentum distributions obtained for Co2MnSi and

Co2MnAlSpecial Session of IWCS2017: ”Design of Novel Magnetic Materials for Device Applications: Simulation and Experiment

17p-2

First-principles study on intrinsic and extrinsic
anomalous Hall conductivity of transition metal alloys
Kazushige Hyodo, and Akimasa Sakuma
Department of Applied Physics, Tohoku University, Sendai, Japanemail: sakuma@solid.apph.tohoku.ac.jp
The anomalous Hall effect (AHE) is one of the unique phenomena in ferromagnetic metals
and has been investigated from physical interests for a long time. Recently, this effect has
attracted particular attention from the field of the “spin orbitronics” due to its close
connection with the spin Hall effect, which is expected to be applied for a new mechanism ofmagnetic reversal with lower energy consumption. However, the systematic understanding of
AHE in real metals still has not been accomplished.
One of the main complexities of AHE in real metals is its multi-mechanisms. The intrinsic
mechanism connects with the Berry phase and has finite conductivity even in the noscattering system. In contrast, the extrinsic mechanism is purely scattering effect and become
divergent in the low impurity limit. Recently, reflecting these backgrounds, the firstprinciples procedure for evaluation of the anomalous Hall conductivity (σxy) including boththe intrinsic and extrinsic mechanisms was presented based on the Kubo-Streda formula [1],which is within the linear-response theory, in the disordered systems [2,3,4].
In the present study, we performed first-principles calculation of σxy based on Kubo-Streda
formula using Tight-binding Linear Muffin-tin Orbital (TB-LMTO) method. Figure 1 shows
the calculated each part of σxy in FePt alloy as a function of degree of order (S) [5]. From thisresult, we confirmed that the skew-scattering part of σxy actually tends to diverge in the limit
of low impurity limit (S ≒ 1 in Fig. 1), whereas, the intrinsic and side-jump parts keep thesteady values in the same limit.

[1] P. Streda, J. Phys. C: Solid State Phys., 15, L717-L721 (1982)[2] S. Lowitzer, D. Ködderitzsch, and H. Ebert, Phys. Rev. Lett., 105, 266604 (2010).
[3] I. Turek, J. Kudrnovský, and V. Drchal, Phys. Rev. B, 86, 014405 (2012)[4] I. Turek, J. Kudrnovský, and V. Drchal, Phys. Rev. B, 89, 064405 (2014)[5] K. Hyodo, Y. Kota, and A. Sakuma, Phys. Rev. B, 94, 104404 (2016)

Special Session of IWCS2017: ”Design of Novel Magnetic Materials for Device Applications: Simulation and Experiment

17p-3

Computational Design of Transition Metal Magnets with
Large Magnetocrystalline Anisotropy
Alexander Edström1,2
1

2

Materials Theory, ETH Zürich, Zürich, Switzerland
Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden

The magnetocrystalline anisotropy energy (MAE) is one of the technologically mostimportant intrinsic magnetic properties. It is crucial in a wide range of applications, ranging
from permanent magnets to magnetic storage devices. The MAE is often strong in rare-earthor actinide compounds, while obtaining a large MAE in 3d-based magnetic materials ischallenging due to the weak spin-orbit interaction. On the other hand, 3d based compounds
would often be preferred in applications. In this talk, potential routes towards increased MAE
in transition metal magnets are discussed and explored using computational methods, largely
based on density functional theory (DFT). Alloying and inducing tetragonality with C or B
dopants is discussed as a path towards increased MAE in FeCo alloys [1,2,3]. The possibility
to improve the MAE of 3d based compounds by including some 5d elements with stronger
spin-orbit interaction is also considered. This is attempted by including small amounts of 5d
impurities in 3d based compounds, such as (Fe1-xCox)2B, where a significant increase in the
MAE and good agreement with experiment is found [4]. Uniaxial 3d-5d compounds, such as
Fe2Ta1-xWx [5], are also discussed.
[1] E. K. Delczeg-Czirjak et al., Physical Review B 89, 144403 (2014).
[2] L. Reichel et al., Journal of Applied Physics 116, 213901 (2014).
[3] L. Reichel et al., J. Phys.: Cond. Matt. 27, 476002 (2015).
[4] A. Edström et al., Phys. Rev. B 92, 174413 (2015).
[5] A. Edström, arXiv:1612.06802.

Special Session of IWCS2017: ”Design of Novel Magnetic Materials for Device Applications: Simulation and Experiment

17p-4
Voltage control of magnetization using magnetoelectric antiferromagnet Cr2O3
sputtered thin film
○T. Nozaki1, M. Al-Mahdawi1, S. P. Pati1, S. Ye1, Y. Shiokawa1, and M. Sahashi1,212Department of Electronic Engineering, Tohoku University, Sendai 980-8579, JapanImPACT Program, Japan Science and Technology Agency, Tokyo 102-0076, Japan

Cr2O3 is the first material which the magnetoelectric (ME) effect is observed in 1960s [1]. However due to its
small magnetoelectric coefficient α, i.e. small electric field induced magnetic moment M = αE, the practicalapplication was not immediately realized. After that, the ME effect in Cr2O3 has captured renewed attention
because the electrical switching of perpendicular exchange bias (PEB) has been demonstrated in bulk Cr2O3 single
crystal/ferromagnet exchange coupling systems in 2005 [2,3]. More recently, the PEB switching was demonstrated
in Cr2O3/spacer/Co all thin film system deposited by the sputtering method [4-6]. Since then, the system hasreceived considerable attentions toward application of an electric writing ultra-low energy consumption
storage/memory applications. The electric switching of PEB can be achieved by following mechanism. By applying
parallel (anti-parallel) electric (E) and magnetic field (H), the antiferromagnetic domain of Cr2O3 align as ↑↓↑↓(↓↑↓↑). If we apply fixed positive H and changing the direction of E from positive to negative, we can switch thedirection of surface spin of Cr2O3 from up (↑) to down (↓). In addition, the surface spin information can betransferred to neighbor ferromagnet via exchange coupling. Thus by combining both the ME effect and PEB, we
can achieve electric control of magnetization. After the observations of the electric switching of PEB in Cr2O3 thinfilm system, we’ve tried to improve the material properties; reduce the switching electric field [7], enhancemagnetic anisotropy [8], propose structure to enhance TN of Cr2O3 [9] etc. Moreover recently Cr2O3 has received
renewed interest as an antiferromagnet, reflecting the development of new detection/manipulation techniques. For
example, ferromagnet free purely antiferromagnetic memory was proposed [10]. Spin Seebeck effect was alsomeasured [11]. We will mainly present our results about the voltage control of magnetization in Cr2O3/Co exchange
biased thin film system, with introducing other recent renewed interest.
This work was partly funded by JSPS KAKENHI Grant Number 16H05975 and ImPACT Program of Council for
Science, Technology and Innovation (Cabinet Office, Japan Government).
References[1] I. E. Dzyaloshinskii, Sov. Phys. JETP 10, 628 (1960).

[2] P. Borisov et al., PRL 94, 117203 (2005).

[3] X. He et al., Nat. Mater. 9, 579 (2010).

[4] T. Ashida TN et al., APL 104, 152409 (2014).

[5] T. Ashida TN et al., APL 106, 132407 (2015).

[6] Y. Shiratsuchi et al., Mater. Trans. 57, 781 (2016).

[7] M. Al-Mahdawi, TN et al., arXiv : 1608.02390.

[8] N. Shimomura TN et al., arXiv : 1605.03680.

[9] Y. Kota et al., IEEE Trans. Magn. 50, 2505404 (2014).

[10] T. Kosub et al., Nat. Commun. 8, 13985 (2017).

[11] S. Seki et al., PRL 115, 266601 (2015).

Special Session of IWCS2017: ”Design of Novel Magnetic Materials for Device Applications: Simulation and Experiment

17p-5

Investigation of spin dependent van der Waals density
functional approach
Masao Obata1,2*, Ikutaro Hamada3, and Tatsuki Oda1,4
1

Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa 920-1192, Japan
2
3

Research Fellow of the Japan Society for the Promotion of Science

International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials
Science (NIMS), Tsukuba 305-0044, Japan
4

Institute of Science and Engineering, Kanazawa University, Kanazawa 920-1192, Japan*E-mail: obata@cphys.s.kanazawa-u.ac.jp

First-principles calculation, which is based on density functional theory (DFT), is one ofestablished method to analyze condensed materials. It also come to be used for material designs
which leads to promote development of novel materials. Investigation of novel materials, i.e. they
have an unclear physical property, by using fist-principles approach, is required the sufficientreliability computational method. However the computational accuracy in DFT calculation
depends too much on the approximation of exchange and correlation energy. Indeed, thecommonly and frequently used approach, based on such as local density approximation or
generalized gradient approximation, cannot describe van der Waals (vdW) force properly.
The van der Waals density functional (vdW-DF) method, which is one of promising methods
to overcome the problem, has been proposed by Dion et al [1]. We have proposed the extension
of vdW-DF to spin-polarized (magnetic) systems, vdW-DF-SGC (SGC means spin-polarizationdependent gradient correction), and demonstrated the usefulness [2]. We also focused on theeffect of SGC which described the spin dependent semi-local electron correlation effect, andfound that it plays an important role in antiferromagnetic interactions.
Another spin van der Waals method (svdW-DF) was developed in 2016 [3]. The relation
between vdW-DF-SGC and svdW-DF should be clarified in several applications. Therefore wealso implemented this method in the house-DFT code, and investigated the oxygen systems andthe absorption system which contains magnetic materials, namely, graphene on Ni(111) surface.
Comparing these results with those of our method, we found that the svdW-DF also corrected theantiferromagnetic coupling and gave almost the same binding property as the vdW-DF-SGC.
[1] M. Dion et al., Phys. Rev. Lett. 92, 246401 (2004).
[2] M. Obata et al., J. Phys. Soc. Jpn. 82, 093701 (2013); 84, 024715 (2015).
[3] T. Thonhauser et al., Phys. Rev. Lett. 115, 136402 (2015).

Special Session of IWCS2017: ”Design of Novel Magnetic Materials for Device Applications: Simulation and Experiment

18a-1

Chiral magnetism in CsCuCl3 probed by polarized
neutron scattering and muon spin rotation
Kazuki Ohishi
Neutron Science and Technology Center,
Comprehensive Research Organization for Science and Society (CROSS)
Numerous experimental and theoretical studies have focused attention on chiralmagnets with antisymmetric Dzyaloshinskii-Moriya interaction, because they provide
opportunities to observe stable magnetic topological structure such as whirls ofmagnetization called skyrmions and a spiral helimagnetic order. Most of inorganicchiral magnetic materials form racemic-twinned crystals, having the right and lefthanded crystalline domains in a specimen so that it is difficult to study the relation
between crystallographic chirality and chirality of magnetic structures. Recently, ourgroup succeeded in controlling the crystallographic chirality and obtained cm-sized
single crystals of chiral helimagnet CsCuCl3 with homo-chirality, namely, enantiopure
crystals. In order to clarify the relation between crystallographic chirality and that ofmagnetic structures in CsCuCl3, we performed polarized neutron diffraction and muon
spin rotation measurements.
We found that the intensity of the magnetic satellite peak at (1/3, 1/3, 6-δ) and (1/3,
1/3, 6+δ) in both chiral crystals depends on the incident neutron spin polarization [1].
Moreover, the muon spin precession frequencies behaves the same temperaturedependence in both crystals, suggesting that the right and left-handed samples are apair of complete isomers in terms of both crystallographic and magnetic structures [2].
These investigations revealed that there is a one to one relationship between the
structural and magnetic handedness in CsCuCl3; namely the right-handed crystal
structure has a right-handed spiral magnetic structure, and left-handed crystal has aleft-handed spiral magnetic structure. In the presentation, we shall discuss in detail the
results of the two experiments.

[1] Y. Kousaka et al., J. Phys.: Conference Series 502, 012019 (2014).
[2] K. Ohishi et al., JPS Conf. Proc. 8, 034006 (2015).

Special Session of IWCS2017: ”Design of Novel Magnetic Materials for Device Applications: Simulation and Experiment

18a-2
Quantum simulation for the motion of positive-muon in materials and its application
for Mu-SR spin state analysis
Hiroshi Nakanishi1,2, Ryan Lacdao Arevalo1, Susan Meñez Aspera1, Hideaki Kasai1,2,3
1National Institute of Technology, Akashi College, Japan

2

Graduate School of Engineering, Osaka University, Japan
3
Institute of Industrial Science, The University of Tokyo, Japan
Abstract
Mu-SR is one of the powerful tools to observe the spin states of atoms in materials [1]. It is
important to know the positive-muon sites, which are the stable or metastable positions ofpositive-muon in the materials, because the spins of muon at such sites can detect the magnetic fieldor effective magnetic interaction with the electron spin in the materials. However, it is difficult to get
information about positive-muon sites using experimental methods. In this case, computer
simulations may give such information, which can complement the Mu-SR data.
Positive muon has the same charge and spin with proton, and has mass 1/9 that of a proton. In
materials, positive muon behaves as the nucleus of the very light hydrogen isotope. Density
functional theory based first principles calculation is one of the most successful and powerful
methods that can be used to decide the atomic positions in materials. For the case of atom with small
mass such as hydrogen, its nuclei should also be treated in a quantum-mechanical manner, in
addition to electrons. The quantum behaviors of the small mass nuclei have crucial roles in theproperties of materials. We have been developing a quantum simulation code “NANIWA” for small
mass atom nuclei on solid surfaces, in subsurfaces, and in bulk crystals [2-6], which can also provide
the positive-muon sites in material.
In the workshop, we will introduce our simulation method and show its results in comparison
with their corresponding experimental data. And we will also discuss its possible application for
Mu-SR spin state analysis.
References[1] S.F.J.Cox, Rep. Prog. Phys. 72 (2009) 116501.
[2] H. Kasai, et al., Progress in Surface Science, 44 (1993) 101.
[3] K. Nobuhara, et al., Surface Science, Vol. 507-510 (2002) 82.
[4] H. Nakanishi, Eds H. Kasai and M. C. S. Escaño (2016) Physics of Surface, Interface and Cluster
Catalysis., Bristol, UK, IOP Publishing, Ch.6-1.
[5] H. Kasai, H. Nakanishi, US Patent 8,140,467 B2 (2012), and JP Patent, 4774523 (2011)[6] H. Kasai, H. Nakanishi, JP Patent, 5902495 (2016)

Special Session of IWCS2017: ”Design of Novel Magnetic Materials for Device Applications: Simulation and Experiment

18a-3

Linear-scaling DFT study on the structural optimization andelectronic properties of real size Ge/Si core-shell nanowires
A

International Center for Materials Nanoarchitectonics (MANA), National Institute forMaterials Science (NIMS), Tsukuba, Japan,
B

University College London, London, UK.

A

J.B. Lin , A. Nakata A, D. R. BowlerB and T. Miyazaki A
Silicon (Si) and germanium (Ge) core-shell nanowires (NWs) as one-dimensional nanomaterial
have many attractive properties for next generation devices. Since there is a lattice mismatch
between Si and Ge, we expect the structure of the NW strongly depends on the diameter of thecore and/or the thickness of the shell. Therefore, we also expect that the electronic properties canbe controlled by varying the diameter of the core and/or the thickness of the shell in the core-shell
NWs. It is very important to clarify and understand how the strains are distributed in the actual
NWs.
In this work, using our linear-scaling or O(N) DFT code CONQUEST, we performed structure
relaxation of the core-shell NWs whose diameters are up to 15nm. The code can perform DFT
calculations on million-atom systems and we can calculate the structural and electronic propertiesof the NWs with the actual size. In this talk, I will report the reliability of large scale DFT
calculations in current system, the strain distributions, and the band structures. The dependence
between strain distribution and the Kohn-Sham eigen orbitals will be also discussed.
This work is done in collaboration with the experimental group headed by Dr. N. Fukata at
NIMS-MANA, and Dr. S. Arapan, Dr. Y. Futamura, Prof. T. Sakurai (Tsukuba Univ.), Dr. C.
O’Roulke and Mr. S. Mujahed (UCL) for theoretical calculations.

Special Session of IWCS2017: ”Design of Novel Magnetic Materials for Device Applications: Simulation and Experiment

18a-4

Nonreciprocal propagation of elementary excitations in
noncentrosymmetric magnets
Yoshinori Onose
Department of Basic Science, University of Tokyo, Japanemail: c-onose@mail.ecc.u-tokyo.ac.jp
Simultaneous breaking of spatial inversion and time-reversal symmetries completely lifts thedegeneracy between +k and -k states of elementary excitations in solids. In this case, thedecay rate and phase velocity depends on the sign of k, and, hence, the propagation of theelementary excitation becomes nonreciprocal. The photonic nonreciprocity, which is denoted
as magnetochiral or optical magentoelectric effect, has been investigated extensively in thelast two decades. Here, we experimentally study the nonreciprocal propagation of magnons
and acoustic waves as well as microwaves in noncentrosymmetric magnets [1-5].
[1] Y. Okamura, Y. Onose et al., Nature communications 4, 2391 (2013).
[2] Y. Nii, R. Sasaki, Y. Iguchi, Y. Onose, arXiv. 1605.07414 (J. Phys. Soc. Jpn. Editor’schoise, in press).
[3] Y. Iguchi, Y. Nii, Y. Onose, arXiv:1607.06889.
[4] Y. Iguchi, S. Uemura, K. Ueno, Y. Onose, Phys. Rev. B 92, 184419 (2015).
[5]R. Sasaki, Y. Nii, Y. Iguchi, Y. Onose, Phys. Rev. B 95, 020407(R) (2017).

Special Session of IWCS2017: ”Design of Novel Magnetic Materials for Device Applications: Simulation and Experiment

18a-5

Theory of spin current generation
Yuichi Ohnuma1,2, Matsuo Mamoru1,2, and Sadamichi Maekawa1,2
1Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195,

Ibaraki, Japan
2ERATO, Japan Science and Technology Agency, Sendai, Miyagi 980-08577, Japane-mail: ohnuma.yuichi@jaea.go.jp

Spintronics is a field aimed at controlling and using the spin degree of freedom of theelectrons. In this field, the spin current, which is the flow of the spin angularmomentum has been extensively studied. Particularly, it is expected that a device
with suppressed energy loss due to the Joule heating can be realized by using the spincurrent.
In order to develop a device using the spin current, it is necessary to establish themethod of spin current generation and to improve its efficiency. The spin pumping
and the spin Seebeck effect, i.e., generation of the spin current in the bilayer systemof a ferromagnet and a metal by applying an oscillating magnetic field and atemperature gradient, respectively, have attracted much attention. Since there is nocharge transfer at the interface, the spin pumping and the spin Seebeck effect are freefrom the impedance mismatch problem which often reduces the spin injection into
semiconductors. The generated spin current is converted into an electric signal by the
spin-orbit interaction in the metal. This phenomenon of conversion from the spincurrent into the charge current is referred to as the inverse spin Hall effect.
In this talk, we show that theoretical investigation of the spin pumping and the spin
Seebeck effect and that material dependence of the spin current [1-3]. In addition, weshow the theoretical study of the inverse spin Hall effect in half-metallic
ferromagnets [4] where the conduction electrons are completely spin-polarized.
Based on our results, we propose the several mechanisms for efficient spin current
generation.

References[1] Y. Ohnuma et al., Phys. Rev. B 89, 174417 (2014).
[2] Y. Ohnuma et al., Phys. Rev. B 87, 014423 (2013).
[3] S. Geprägs et al., Nat. Commun. 7, 10452 (2016).
[4] Y. Ohnuma et al., Phys. Rev. B 94, 184405 (2016).

Numerical simulation for dynamical elastic contact problem
Yoshiho AKAGAWA
Kanazawa University Graduate School of Natural Science and Technology
Mathematical and Physical Sciences (yoshiho_akagawa@stu.kanazawa-u.ac.jp)
The purpose of this work is to present a model which describes dynamical elastic contact. We
aim for the model which can reproduce a collision of rolling ball, a motion of tire on road, andstick-slip with PDEs. Stick-slip occurs, for example, from an inter action of roller and paper(sheet feeder). It is easy to suppose that friction and restitution coeﬃcient are related withthis phenomenon, but it seems that another are related with. We adopt new points which areadhesion force, surface tension force, and hysteresis of friction. We investigate how to describe
these points as PDEs. In this presentation, especially, we focus on surface tension force.
In order to obtain numerical solutions, we employ discrete morse flow(DMF) which is betterfor global constrain. Let Ω ⊂ R2 be an open domain with smooth boundary and ΓD ∪ ΓK =∂Ω, ΓD ∩ ΓK = ∅. (u = (u1 , u2 ), x = (x1 , x2 )). σ and ε are stress tensor and strain tensor
respectively.
∫∫|u − 2um−1 + um−2 |21
Jm (u) =dx +σ(u) : ε(u) dx + S(u),m = 1, 2, · · ·
2h2
2 Ω
Ω
Km := {z ∈ H 1 (Ω; R2 ); z = gm on ΓD , z 2 (x) + x2 ≥ 0 for x ∈ ΓK }u−1 and u0 are given functions, um , m = 1, 2, · · · is a minimizer of Jm on Km . surface tension
force is defined by∫∫S(u) :=

ΓK

γ1 |ps | ds +ΓK

γ2 χ{p2 >0} |ps | ds

where p(x) = u(x) + x for x ∈ Ω. γ1 = γSL − γSG and γ2 = γLG − γSL + γSG are surface tension
coeﬃcients. The minimizer satisfies the followings:

σ(u)n = −γLG κ|ps |ν12(σ(u)n) = 0, (σ(u)n) ≥ 0γLG t1 = γSL − γSGon ∂Ω ∩ {p2 > 0}on ∂Ω ∩ {p2 = 0}on ∂Ω ∩ ∂{p2 > 0}

where n is an unit outer normal vector of ∂Ω, t := ps /|ps |, and ν = −ts /|ts |.
Numerical result of a weak coupling with Coulomb friction model
































































For numerical results, we could not observe a vibration which likes stick-slip. In future, we focus
on adhesion and hysteresis of friction.

SMOOTHED PARTICLE HYDRODYNAMIC SIMULATIONOF ACCRETION DISK IN CATACLYSMIC VARIABLE
SAEFUL AKHYAR*
Supervisor: Prof. Seiro Omata
Division of Mathematical and Physical Sciences, Kanazawa University*saeful.akhyar99@gmail.com

ABSTRACTAn investigation on accretion disk in cataclysmic variable stars (CVs) becomes aninteresting phenomenon in astrophysics since one of its effects, the oscillation of the brightnessof the light curve from photometric has been observed. Since the disk of CVs is the brightest
component of the system, it is believed that the oscillation might come from mass transfer of
the accretion process. In this research, we use an SPH (Smoothed Particle Hydrodynamics)
method to visualize the generation process of an accretion disk in Cataclysmic Variables.
Since introduced by Lucy (1977) and Gingold & Monaghan (1977), SPH is widely used
to simulate many astrophysical phenomena. SPH is a Lagrangian method which discretizes thecontinuum into a set of particles. In this research we simulate the system of binary stars withmass ratio 1:0.08 𝑀⊙ and short rotation period (1000s). For the sake of simplicity, we consider
our continuum as an ideal gas, and ignoring the magnetic effect of the stars. Variation ofbolometric luminosities is determined by summation of the changes in the internal energies ofall particles in each time steps.
Keywords: accretion, accretion disks - hydrodynamics - binaries: close - methods: numerical- novae, cataclysmic variables

First-Principles Study of Electronic, Magnetic, and Optical
Properties of Nickel Cobaltite: DFT and QSGW methods
Hasan Al Rasyid1, Masao Obata1,2, Nurul Iksan1, Takao Kotani3, and Tatsuki Oda1,4
1

Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa 920-1192, Japan
2
Research Fellow of the Japan Society for the Promotion of Science3
Department of Applied Mathematics and Physics, Tottori University, Tottori 680-8552, Japan
4
Institute of Science and Engineering, Kanazawa University, Kanazawa 920-1192, Japan

Nickel cobaltite (NiCo2O4) is one candidate of novel materials that could be engineered in many
ways to exhibit different properties. For example, by utilizing temperature growth of less than
450oC, ones can acquire metallic-ferrimagnetic NiCo2O4 thin film. On the contrary, with morethan 450oC, we would acquire that film as non-magnetic insulator [1]. This uniqueness is believed
to come from the competition between double exchange interaction among cations with different
charges and superexchange interaction among those with same charges [2]. Nickel cobaltite isalso predicted to be half metallic, due to the existence of a band gap on its majority-spin stateband.
We employed first-principles density functional theory (DFT) and quasiparticle self-consistent
GW method (QSGW) to elucidate electronic, magnetic and optical properties of different types of
NiCo2O4 predicted bulk structures. There are some discrepancies arising between GGA andQSGW methods in addressing double exchange and superexchange interaction. In this regards,
QSGW described more accurate electronic structure. These results also compared with those of
more well-known materials, i.e. Fe3O4 and Co3O4.We considered three possible bulk structures of
Nickel cobaltite, namely normal spinel, type-A inverse spinel, and type-B inverse spinel. BothGGA and QSGW predicted half-metallicity of type IB with indirect band gap at majority channel
exhibited by Table 1. In addition, optical properties of NiCo2O4 also investigated by calculating
dielectric function and comparing it with experiment optical absorption spectra.
Table 1. Band gap in the majority-spin state for different NiCo2O4 structure probabilities(with experiment data).
MethodBand gap of different Spinel Structures (eV)NormalType-A inverse

Type-B inverse

GGA

0.89

0.87

0.90

QSGW

1.07

1.25

1.36

Expt.[3]0.38 – 1.42 (Indirect)[1] P. Silwal, et al., Applied Physics Letters, 100, (2012), 032102.
[2] Y. Bitla, et al., Scientific Reports, 5, (2015), 15201.
[3] K. Dileep, et. al., J.Phys. D: Appl. Phys. 47, (2014), 405001.

Holonomic Gradient Method for the Distribution Functionof the Largest Root of Complex Non-Central Wishart
Matrices
Fadil Habibi Danufane1
1

Katsuyoshi Ohara2

Nobuki Takayama3

Indonesian Institute of Sciences, Kanazawa University (fadi002@lipi.go.id)
2
Kanazawa University (ohara@air.s.kanazawa-u.ac.jp)
3
Kobe University (takayama@math.kobe-u.ac.jp)

We evaluated the outage probability of multiple-input-multiple-output (MIMO) systems employing maximal ratio combining (known also as beamforming systems) and operating over
Rician-fading channels using a relatively new numerical method called Holonomic Gradient
Method (HGM).
In conventional wireless communications, a single antenna is used at the source and anothersingle antenna is used at the destination. In some cases, this gives rise to problems with multipath
effects which can cause a reduction in data speed and an increase in the number of transmission
errors. One of the solutions to this problem which is very popular among telecommunicationengineers is the use of two or more antennas, hence the MIMO system.
The outage probability is an important statistical measure to assess the quality of service
provided by the system. It is defined as the probability of failing to achieve a specified Signal
to Noise Ratio (SNR) value sufficient for satisfactory reception. It is known that the outage
probability can be expressed as the Cumulative Distribution Function (CDF) of the largest
eigenvalue of a non-central Wishart Matrix.
In the past years, there have been several attempts to compute the outage probability using
method such as Monte-Carlo or power series expansion [1]. However, those computations are
relatively slow. This disadvantage becomes more apparent especially when we want to perform
a computation over several threshold values or when a large number of antennas is involved.
We would like to develop a new method that can perform this computation for several valueof quickly for a large number of antennas. We found that outage probability of MIMO system
can be expressed as a holonomic function. Thus, we use this fact and use HGM as this method
is known to be faster and more efficient than other alternatives in doing a computation involving
a holonomic function [2].
The HGM consists of three steps: (1) Finding a holonomic system satisfied by the function
and translating it to a Pfaffian system. (2) Finding an initial value vector for the Pfaffian system.
(3) Using the obtained Pfaffian system to evaluate the function numerically at several points by
the Runge-Kutta method.
Our result shows that HGM is a faster and more efficient method than Monte-Carlo andpower series expansion for computing the CDF of the largest eigenvalue of a non-central Wishart
Matrix. It is shown by the computation time and the number of antennas that this method canhandle without compromising the computation time too much. As a validity check, we compare
our result with the one that appears in some previous research publication. We found that thegraph of our result agrees with the one in the paper.

References[1] Ming Kang, Mohamed-Slim Alouini, Largest Eigenvalue of Complex Wishart Matrices andPerformance Analysis of MIMO MRC Systems, IEEE Journal on Selected Areas in Communications, 21 (2003), No. 3, 418–426.
[2] Hiroki Hashiguchi, Yasuhide Numata, Nobuki Takayama, Akimichi Takemura, Holonomic
gradient method for the distribution function of the largest root of a Wishart matrix, Journalof Multivariate Analysis, 117, (2013) 296–312

1

First-principles study on θ-phase in solid oxygen
Yosuke Funato1 , Masao Obata1 , and Tatsuki Oda1,2
1

Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa
920-1192, Japan

2

Institute of Science and Engineering, Kanazawa University, Kanazawa 920-1192, Japan
Email address: funato@cphys.s.kanazawa-u.ac.jp (Y. Funato),
oda@cphys.s.kanazawa-u.ac.jp (T. Oda)

Oxygen molecules, which are indispensable to living organisms, provide interesting
themes not only in the field of earth science, biology, chemistry, but also in condensed
matter physics. This is because oxygen molecule has rare features with spin quantum
number S=1 among simple homonuclear diatomic molecules, and also because both ofvan der Waals force and magnetic intermolecular force play an important role in thecondensation of molecules. As a consequence, the crystal structure is determined under asubtle balance. Solid oxygen changes its crystal structure by the external parameters suchas temperature and pressure. Seven phases (α, β, γ, δ, ε, ζ, η) have been discovered so far.
Recently, experimental studies on the one-turn coil method indicated that themagnetization rapidly changes under a high external magnetic field (around 120 T) [1].
It is suggested that this has undergone a phase transition to a new structure (θ-phase).
This phase, in which there are ferromagnetic correlation and intermolecular sequence like
S-type or X-type, is expected to be a different phase from conventional solid oxygen. In
order to elucidate its structure, we investigated several types of crystal structures by using
the first-principles approach which employs the vdW density functional as the exchange
correlation energy.
We calculated the cohesive energy of dry ice structure and iodine structure considered
as candidates for θ-phase, assuming ferromagnetic state. The volume of θ-phase, which
expands under a strong magnetic field, was estimated to be about 15% larger than that of
α-phase. This result corresponds well to those of experimental data, indicating that thecomputational approach supports the dry ice structure as the most probable candidate.

[1] T. Nomura et al., Phys. Rev. Lett., 112, 247201 (2014).

Title : Numerical study of an adaptive Lagrange-Galerkinscheme for pure convection problems
Authors : Kouta Futai*, Hirofumi Notsu
Affiliation of the authors : Kanazawa University(email address : futai.k.1275@stu.kanazawa-u.ac.jp)
Abstract :The Lagrange-Galerkin (LG) scheme is a combination of thefinite element method and the method of characteristics, and is
known as one of the powerful numerical methods for flow
problems.
Introducing an adaptive mesh refinement technique, we have
implemented an adaptive LG scheme for pure convection
problems.
In the poster numerical results of the scheme are presented andthey are studied from the view points of computation cost andaccuracy.

Theoretical study on multi-functional Fe/MgO interface:
investigation of perpendicular magnetic anisotropy origin
Nurul Ikhsan,1 Tomosato Kanagawa,1 Indra Pardede,1 Masao Obata,1,2
Tatsuki Oda1,3
1

Graduate School of Natural Science and Technology, Kanazawa University, Kakuma
920-1192, Japan
2
Research Fellow of the Japan Society for the Promotion of Science
3
Institute of Science and Engineering, Kanazawa University, Kanazawa 920-1192,
Japan
Email address: ikhsan@cphys.s.kanazawa-u.ac.jp (N. Ikhsan)

Multi-functional thin film of iron/MgO interface has a lot of interesting physicalproperties and potential application for magnetic and magnonic devices. Its uniquemagnetic characteristic, perpendicular magnetic anisotropy, voltage/spin-current controlled magnetic anisotropy, also unique spin structure with voltage controlled Dzyaloshinskii-Moriya interaction [1]. This feature is promising for information technology
device, especially for high density and low power consumption data storage. Anotherpossible application of the spin waves in this interface can be used for higher frequency(more than Tera Hertz) of RF devices [2], because its have several orde of magnitude
shorter wavelength. The latter thin film also can be used for information bus and logic
gate for future integrated signal-processing magnetic device.[1]Such data sotrage/memory can be created by utilizing novel concept of the voltage
controlled perpendicular MTJ. Even though the technology is seems to be mature,
but there is still a lot of room for improvement. For example, the large perpendicularmagnetic anisotropy (PMA) is required to keep the device stable under thermal fluctuation and high temperature of fabrication process. Current value of PMA is below 1
mJ/m2 [3], this still need to be improved in order to ensure the stability and prevent
deterioration of the memory cell due to aging and disturbance of external field.
This work performed basic re-investigation of this interface to find the mechanismof how PMA can be found. The calcualtions of density functional theory (DFT)and dipole interaction energy correction were carried out to estimate the magnetic
anisotropy energy (MAE) of ultrathin multilayer iron film, Fe/MgO interface, and the
Fe/MgO interface with Chromium (Cr) buﬀer layer. The high density of k sampling
point with spin-orbit interaction was taken into account in the DFT.
Calcualtion reslut showed the interface system demonstrates high perpenducularmagnetic anisotropy energy. The electronic structure near the Fermi level provides
important information to the magnetic anisotropy properties. Basic mechanism ofperpendicular magnetic anisotropy based on second order perturbation theory is used to
explain the large positive contribution to MAE. Our results encourage experimentalist
to challenge more advanced fabrication to realize various properties on MAE.
This work was supported by ImPACT Program of Council for Science, Technology and Innovation(Cabinet Oﬃce, Japan Government) and by the Kanazawa University SAKIGAKE Project.

[1] K. Nawaoka et al., Appl. Phys. Exp. 8, 063004 (2015).
[2] V. V. Kruglyak et al., J. Phys. D: Appl. Phys. 43, 264001 (2010).
[3] T. Nozaki et al. (2016). Phys. Rev. Appl. 5, 044006 (2016).

First principles calculation of magnetic anisotropy energy on
double interfaces slab systems of X/Fe/MgO
Tomosato Kanagawa1*, Nurul Ikhsan1, Indra Perdede1, Masao Obata 1, Tatsuki Oda1,2
1

Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi,
Kanazawa 920-1192, Japan
2
Institute of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 9201192, Japan*E-mail: kanagawa@cphys.s.kanazawa-u.ac.jp

There is an important purpose to develop a non-volatile random access memory due
to advanced information oriented society. Magnetic random access memory (MRAM) is
one of the most desirable candidates. MRAM drives based on spin orientation of memory
cells and the energy barrier to spin orientation is called magnetic anisotropy energy(MAE). High MAE is necessary for thermal resistivity to keep the memory [1], but it
consumes high energy for data rewriting. Magnetoelectric random access memory(MeRAM) can variate MAE by electric field and the rate of variation is called voltage
control magnetic anisotropy (VCMA) [2]. High VCMA is desirable to achieve replacing
current RAM. The MAE is originated from spin-orbit coupling (SOC) and magnetic
dipole-dipole interaction (MDI). Recent magnetic memory requires a perpendicularmagnetization due to realizing a small size of memory cell. In this work, we focus on thecontribution of SOC because the MDI contributes to the favor of in-plane magnetizationand is not expected to change under the electric field. The Fe/MgO interface is essential
for MeRAM owing to several reasons, e.g. high tunneling magnetic resistance ratio, easy
to fabricate, perpendicular magnetization, etc. However, it is difficult to analyze theinternal electronic structure experimentally. So far, many theoretical approaches havebeen accomplished in the properties of MAE and VCMA [3,4].
We studied the slab systems of X/Fe/MgO (metal for X) with double interfaces. Suchsystem keeps the Fe/MgO interface and has possibility to improve MAE by intrinsic
deflection of the under layer (X). We estimated MAEs and VCMAs in X/Fe/MgO byusing first-principles calculation and analyzed the electronic structures. The calculation
results revealed a more concrete relation between electronic structures and MAE.
This work was supported by ImPACT Program of Council for Science, Technology andInnovation (Cabinet Office, Japan Government) and by the Kanazawa University SAKIGAKE
Project.

[1] H. Ohno et al., Nat. Mater. 9, 952 (2010).
[2] T. Nozaki et al., Phys. Rev. Appl., 5, 044006 (2016).
[3] M. Tsujikawa and T. Oda, Phys. Rev. Lett., 102, 247203 (2009).
[4] D. Yoshikawa et al., Appl. Phys. Express, 7, 113005 (2014).

Numerical simulation of contact problem of an elastic
body with friction.
Hiroyuki Kitano
Kanazawa University,
Graduate School of Natural Science and Technology,
Division of Mathematical and Physical Sciences.
M2 (iambeat8@yahoo.co.jp)
We simulate contact problem of an elastic body with friction.
We introduce a way how to manage friction force artiﬁcially for thecontact problem on the numeric.
Step 1: We ﬁnd numerical solution of contact problem without friction.
Step 2: We consider an eﬀect of friction from the solution of step 1.
Step 3: We set a boundary condition from the eﬀect which we got in step2.
Step 4: We ﬁnd numerical solution of contact problem with the boundary
condition of step 3.
We do numerical calculation in that way, and get the result consideredthat there is an eﬀect of friction. However, we introduce friction on the
numeric artiﬁcially, so the solution doesn’t always satisfy the governing
equation. We suppose that further studies are needed about how to deal
with friction.

1

Hyperfine structure of muonium in GaN
Susumu Minami1*, Mineo Saito2 , Fumiyuki Ishii2, Hiroyoshi Momida3
and Tamio Oguchi3
1

Division of Mathematical and Physical Sciences, Graduate School of Natural Sciences andTechnology, Kanazawa University, Japan
2

Facaulty of Mathematics and Physics, Institute of Science and Engineering,
Kanazawa University, Japan
3

Institute of Scientific and Industrial Research, Osaka University, Japan
Corresponding author: minami@cphys.s.kanazawa-u.ac.jp

GaN is one of the important wide gap semiconductors. Its wide-band gap of 3.4eV affords its
special properties for applications in electronic and optoelectronic devices, e.g., bright, highly
efficient blue and green light-emitting diodes. It is well known that hydrogen contributes topassivation in the case of p-type doping. However, the electronic and atomic structures ofmono-hydrogen in GaN is still unclear. An µSR experiment detected neutral paramagnetic
muonium which has a shallow donor level, suggesting that hydrogen can be a shallow donor[1]. However, first-principles calculations indicate that hydrogen has a negative-U property[2,3].
An µSR experiment shows a strong anisotropic hyperfine structure[1], which is a key point
to identify the atomic site of muonium which is expected to be the same as the stable site ofhydrogen. In this study, we perform first-principles calculations of atomic and electronic
properties of mono-hydrogen in GaN. We use generalized gradient approximation based on thedensity functional theory. A plane wave and pseudopotential are used. After that, we calculate
hyperfine parameter by using all-electron calculation. Calculation code HiLAPW is used.
We find that the spin density is not simply localized at thehydrogen site, i.e., we find substantial spin densities at six N
atoms which are near the hydrogen (see the figure).
Furthermore, our calculation result reproduced anisotropic
hyperfine parameter. Finally, this spin density distribution is
expected to be consistent with the anisotropic hyperfine
structure which was observed by using µSR.
[1] K. Shimomura, R. Kadono,, K. Ohishi, M. Mizuta, M. Saito, K. H. Chow, B. Hitti, and
R. L.Lichti,. Phys. Rev. Lett. 100, 111111 (2014).
[2] J. Neugebauer, and C. G. Van de Walle, Phys. Rev. Lett. 75, 4452 (1995).
[3] A. F.Wright, Phys. Rev. B., 60, R5101 (1999).

On the prediction of storm surge along the coast of Bangladesh
Md. Masum Murshed1,2, Gour Chandra Paul1
1. Department of Mathematics, University of Rajshahi, Rajshahi 6205, Bangladesh
2. Department of Mathematics, Kanazawa University, Kanazawa, Japan
Email: mmmurshed82@gmail.com, gcpaul@ru.ac.bd

Speaker: Md. Masum Murshed

Abstract
In this study, a shallow water model in Cartesian coordinates is developed to predictwater level due to surge associated with a storm along the coast of Bangladesh. The
developed equations are solved by a conditionally stable explicit finite difference method
using an Arakawa C-grid. The coastal and island boundaries are approximated throughproper stair step representations. Nested numerical technique is exercised to solve
computational complexities as well as to save computational cost. A stable tidal regime isgenerated by forcing the sea level to be oscillatory with the most dominating constituent
M2 of the region of interest along the southern open boundary of the outer model.
Numerical experiments are done with the two typical tropical storms April 1991 andAILA, 2009. The model results, so far obtained, are found to be in good agreement withthe data by Bangladesh Inland Water Transport Authority (BIWTA) and some reporteddata.

3D simulation of crack propagation in
an elastic body by a phase field model
Takumi Nakano
Kanazawa Univ. M1 (takumi1228@stu.kanazawa-u.ac.jp)
M.Kimura (Kanazawa Univ.)
T.Takaishi (Hiroshima Kokusai Gakuin Univ.)

In this study, we perform 3D simulation of crack propagation in anelastic body by using FreeFem++. A phase field function is introduced
in order to deal with crack growth flexibly.
In the simulation the dependency of the crack growth on the fracture
toughness of the material is investigated.

An Implicit Boundary Integral Method for
Laplace Problem
Irma Palupi∗
Department of Mathematics and Physics, Kanazawa University
E-mail: irma.palupi@gmail.com

Abstract
In this work, we consider boundary integral method to solve Laplace Dirichletboundary problem. A few results from layer potential theory are used to construct asolution in the form of Double-Layer potential and Single-Layer potential for simple
connected domain and for multi-connected domain. In order to find the density function and to construct the solution using boundary integral form, we use the idea ofusing Coarea formula and signed distance function representation to reformulate theboundary integral into a Riemann integral, such that it does not depend on any parameterization to describe the boundary. We also present the algorithm how to technicallywork with this method and show a few numerical results.
Keywords: Boundary Integral Method, Laplace Dirichlet problem, layer potential integral, level set method

1

FINITE ELEMENTS METHOD OF ERGODIC
DISTRIBUTION FUNCTION FOR JAFFE MODEL
RISKA WAHYU ROMADHONIA*
Supervisor : Prof. Seiro Omata
Division of Mathematical and Physical Sciences, Kanazawa University*riskaa.wahyu@gmail.com
ABSTRACT
Finite element method (FEM) has been widely used for solving in mathematical physics problem. In this study, we aim to use FEM to constructdistribution function (DF) of stellar system. This method has been propose
by Jalali (2007).The method is the generalization of Schwarschild‘s method.
Unlike Schwarschild‘s method, this method provided a continuous DF andused two finite elements meshes, which is in configuration space and in action space. We also show the performance of FEM for spherically symmetricsystem by ergodic DF Jaffe model (Jaffe 1983). For the sake of simplicity,
we generated the finite element mesh with simple double-node elements andlinear interpolating functions.
Keywords : Finite element method, galaxies : structure, Jaffe model

1

NUMERICAL METHOD OF NONLINEAR BLACK SCHOLESEQUATION FOR AMERICAN OPTIONS PRICINGAYU SHABRINA*
Supervisor : Prof. Seiro Omata
Division of Mathematical and Physical Sciences, Kanazawa University*ayushabrina@gmail.com
ABSTRACTThe aim of this work is to calculate American options price with transaction costs from the Black Scholes model. Due to transaction costs, large investor preferences and incomplete markets, the classical Black Scholes model
become unrealistic and results nonlinear, possibly degenerate, parabolic convection diffusion equations, where the volatility σ and the drift µ can depend on the time t, the stock price S or the derivatives of the options price(Ankudinova, 2008). In this work, several of volatility model will be usedand compared to show the influence of transaction costs. The option pricing
problem from nonlinear Black Scholes equation will be solved numericallyusing finite difference scheme combined with an operator splitting techniqueproposed by Ševčovič (2008).
Keywords : American options, Nonlinear Black Scholes equation, Volatility
model

1

Computation of an inverse free boundary problem for a shape
optimization method
Shogen Shioda, Masato Kimura
Kanazawa University
e-mail : sho02345@stu.kanazawa-u.ac.jp

Numerical results of an inverse free boundary problem by a shape optimization method arepresented and the eﬃciency is studied.
Many shape optimization methods have been proposed and studied. The traction method isknown as one of the powerful methods for shape optimization problems. We apply the shape
optimization method by traction method to an inverse free boundary problem.

A gradient flow structure of the Maxwell-type viscoelastic modeland its finite element analysis
Hiroki Yamamoto , Masato Kimura , Yoshimi Tanaka , Hirofumi Notsu.
Kanazawa university (mos@stu.kanazawa-u.ac.jp)

The viscoelastic material has both viscosity and elastic eﬀects.The Maxwell-type viscoelastic
model is a system of partial diﬀerential equation defined by the series connection of spring anddashpot. This model can represent the stress relaxation phenomenon. In the poster we show
the gradient flow structure of the model and propose a finite element scheme presenting thestructure.

4 way-hexagonal symmetric crystalline method and 2
dimensional snow crystal model allowing collision /splittingYamaoka Ryohei,Tanaka Tomoe
In this research, we aim to construct a mathematical framework of 2 dimensional
crystal growth model which allows side collision and split like snow crystal growth. Basedon the mathematical formulation of the Crystalline method expanded to include splitting
and collision of sides of hexagonal crystals made in the previous study, a quadrilateral
growth model is considered. The numerical calculation is performed on the crystal growthmodel.

Development of a finite element method for adelamination model and its simulation
Takuro Yoneda
Kanazawa Univ. M1 (ismbr-0410@stu.kanazawa-u.ac.jp)
In this study, we develop a finite element method for the delamination model proposed in[R.Scala , ESAIM : COCV , 2017] and present numerical results by the method. Two elastic
bodies are glued by an adhesive and the delamination process induced by vibration in considered. The glue plays a role of “spring”, and the delamination occurs when the difference of thedisplacements of two bodies exceeds a threshold.

1

Minimum energy state and gradient flow forinteraction energy of particles
Yang Zhenxing
Kanazawa University(y zhenxing@yahoo.co.jp)
Abstract
We are interested in minimum energy state of interacting particles. We haveshowed that there exist a minimum energy when the particles get a equilibrium
state in one and two dimension, now we take a domain that contains particles andwe want to find the minimum energy state by making the gradient flow from thefunction of energy of particles.

1