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(Last update: 2024.04.11)

Mochizuki Group

We are theoretically exploring physical phenomena and device functions of materials such as magnets, electrics, superconductors, metals and insulators. Our starting points are microscopic models, which describe kinetics and interactions of electrons in materials based on quantum mechanics. The electrons have charge, spin, and orbital degrees of freedom, which mutually couple and correlate. Taking account of the interplays between these degrees of freedom, we construct mathematical models for the materials and analyze thus constructed models using quantum mechanics, statistical mechanics, quantum field theory, and numerical techniques. In this way, we reveal rich physics behind spectacular phenomena of materials and predict novel physical properties and materials functions. Properties of individual electrons are understood well, which faithfully obey quantum mechanical laws. However, once many electrons gather, the situation is no longer the same as the case of a single electron, because of keen competition and cooperation among them. Assembly of vast amounts of electrons show drastic and rich physical phenomena, e.g., magnetism, phase transitions, superconductivities, colossal magnetoresistance. We attack these inconceivable and spectacular phenomena with pencils, papers, computers, and enthusiasms.

Highlights

[048]``Controllable creation of skyrmion bags in a ferromagnetic nanodisk [049]``Theory of Magnetic Vortex Crystals Induced by Electric Dipole Interactions [050]``Reversible magnetic domain reorientation induced by magnetic field pulses with fixed direction [051]``Spontaneous Vortex-Antivortex Pairs And Their Topological Transitions in A Chiral-Lattice Magnet [052]``Laminar and Quasi-Turbulent Dynamics of a Magnetic Skyrmion Pipe Flow [053]``Handwritten digit recognition by spin waves in a Skyrmion reservoir [054]``Chiral Skyrmions Interacting with Chiral Flowers [055]``Global rotation of skyrmion bags under vertical microwave fields

News



icon 2024.04.28
Prof. Mochizuki gave an invited talk at the 9th International Conference on Superconductivity and Magnetism (ICSM2024) held at Liberty Hotels Lykia in Ölüdeniz, Turkey (27th April - 4th May, 2024).

Title:Thermally Induced Dynamics of Magnetic Skyrmions and Their Device Functions

icon 2024.04.10
Dr. Charles Reichhardt (Los Alamos National Laboratory, USA) gave a seminar talk[Abstract], [Album].
Date:2024.04.10(Wed.) 10:45
Place:Bldg. 55N, 2F, Meeting Room, Nishi-Waseda campus, Waseda University
Title:Dynamics of Chiral Systems, Vortices, Skyrmions, and Active Matter
Speaker:Dr. Charles Reichhardt(Los Alamos National Laboratory, USA)
icon 2024.04.01
Tatsuki Muto (D1) has been appointed as a research associate, and four new members have joined our group[Member]. The new members are as follows, Yusuke Kobayashi (M1), Manaki Arihara (B4), Hironosuke Kobayashi (B4), and Aoba Yasuda (B4).

icon 2024.03.31
Prof. Masatoshi Imada(Visiting Research Prof.),Ryui Kaneko(Research Associate Prof.),Aya Kitano(Secretary of Imada group)left our group.

icon 2024.03.26
Two students, Takaaki Iijima and Tatsuki Muto, have completed their master's degree in the Department of Physics and Applied Physics at Waseda University[Album].

icon 2024.03.26
Three students, Yuki Akishige, Tatsuya Iguchi, and Ryo Hamano, graduated from the Department of Physics and the Department of Applied Physics at Waseda University[Album].

icon 2024.3.22
A farewell party was held at a Chinese restaurant (皇家龍鳳) in Rihga Royal Hotel [Album].

icon 2024.03.23
The following oral presentation will be given in the 71st Spring Meeting of the Japan Society of Applied Physics (JSAP)(Tokyo City University, Setagaya campus + Online).

Numb.: 23p-22B-10
Title: Proposal of a mathematical model of amoeba-inspired combinatorial optimization machines: simplification towards physical implementations
Speakers: Yusuke Miyajima, Masahito Mochizuki

icon 2024.03.18-20
The following oral presentations will be given in 2024 Spring Meeting of the Physical Society of Japan (Online),

Numb.: 18pC1-5
Title: Theoretical study of photoinduced magnetic phase transition and photoinduced topological magnetism in the J1-J3 classical Heisenberg model on a triangular lattice
Speaker: Takaaki Iijima, Masahito Mochizuki

Numb.: 18pL2-13
Title: Improved mathematical model of amoeba-inspired combinatorial optimization machines
Speaker: Yusuke Miyajima, Masahito Mochizuki

Numb.: 20aC2-5
Title: Interaction engineering: Anharmonic effects on magnons in the sawtooth chain antiferromagnet Fe2Se2O7
Speaker: Rintaro Eto, Masahito Mochizuki, Alexander Mook

icon 2024.03.15
The following poster presentations will be given in the 22nd Japan-Korea-Taiwan Symposium on Strongly Correlated Electron Systems (JKT22).

Numb.: PS-10
Title: Interaction engineering: Anharmonic effects on magnons in the sawtooth chain antiferromagnet Fe2Se2O7
Presenter: Rintaro Eto

Numb.: PS-26
Title: Theory of chiral damping in ferromagnetic and antiferromagnetic textures
Presenter: Collins Akosa

Numb.: PS-36
Title: Theoretical study of the photoinduced magnetic transition in the Kondo lattice model
Presenter: Ryo Hamano

icon 2024.03.07
Keisuke Kitayama (former graduate student) will give an oral talk in American Physical Society (APS) March meeting 2024 held at Minneapolis convention center in Minneapolis, MN, USA.

Numb.: S04.00003
Title: Predicted Novel Type of Photoinduced Topological Phase Transition Accompanied by Collision and Collapse of Dirac-cone Pair in Organic Salt α-(BEDT-TTF)2I3
Speakers: Keisuke Kitayama, Masao Ogata, Yasuhiro Tanaka, Masahito Mochizuki

icon 2024.03.02
Yusuke Miyajima(D2) gave a poster presentation in the 5th International Symposium on Neuromorphic AI Hardware[web] held at Rihga Royal Hotel Kokura in Kitakyushu, Fukuoka in 3/1-2.

Title: Proposal of computational models of Amoeba-inspired combinatorial optimization machines
Presenters: : Yusuke Miyajima, Masahito Mochizuki

icon 2024.2.29
The KAKENHI project "Chimera Particles" (led by Shuichi Murakami, Tokyo Institute of Technology), in which Mochizuki participates as a member of the project team, has been accepted.

icon 2024.02.13
The following paper was published in Journal of Applied Physics. In this work, we focused on topological magnetic structures called skyrmion bags, in which multiple small skyrmions exist inside a large skyrmion. Using micromagnetic simulations, we discovered a phenomenon that microwave excitation induces global rotation of the inner skyrmions and elucidated its physical mechanism.

Lan Bo, Rongzhi Zhao, Xichao Zhang, Masahito Mochizuki, Xuefeng Zhang
Journal of Applied Physics 135, 063905/1-6 (2024).

Title: Global rotation of skyrmion bags under vertical microwave fields
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icon 2024.02.03
The graduation thesis presentations of the Department of Applied Physics and the Department of Physics were held. Three students from our group, Yuki Akishige, Tatsuya Iguchi, and Ryo Hamano, gave presentations.

【Bachelor Thesis Titles】
Yuki Akishige ``Theory of Photoinduced Polarization Domain Dynamics in Proton-Transfer Ferroelectrics"
Tatsuya Iguchi ``Theoretical study of magnetic resonance excitations in antiferromagnetic NiO"
Ryo Hamano ``Theoretical study of photoinduced magnetic transitions in Kondo-lattice magnets"

icon 2024.02.04
The master's thesis presentations of the Department of Physics and Applied Physics were held. Two students from our group, Takaaki Iijima and Tatsuki Muto, gave presentations.

【Mater's Thesis Titles】
Takaaki Iijima ``Theoretical study of photoinduced magnetic phase transitions and photoinduced topological magnetism in the J1-J3 classical Heisenberg model on a triangular lattice"
Tatsuki Muto ``Elucidation of stabilization mechanisms and exploration of physical properties of skyrmions in magnetic dipolar systems"

icon 2023.12.18.
Rintaro Eto (Ph.D student) was selected for the JSPS 2024 Young Researcher Overseas Challenge Program [web].

icon 2023.12.18
Lan Bo (visiting student) has left from our group after a one-year stay. We wish him all the best in his future endeavors.

icon 2023.12.6
The following paper was published in Nano Letters. In this work, we discovered that when magnetic skyrmions are confined in an obstacle pattern called chiral flower, they exhibit one of the typical active-matter behaviors called chiral swimmer due to the Brownian motion with broken rightward and leftward symmetry in numerical simulations and uncovered a physical mechanism behind it. The discovery of active matter behavior, which is conventionally exhibited only by materialsof biological origin, in skyrmions is expected to lead to new development of the research for active matters.

Xichao Zhang, Jing Xia, Oleg A. Tretiakov, Motohiko Ezawa, Guoping Zhao, Yan Zhou, Xiaoxi Liu, Masahito Mochizuki
Nano Letters 23, 11793-11801 (2023).

Title: Chiral Skyrmions Interacting with Chiral Flowers
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Press release(2024.2.13)

Scientists study the behaviors of chiral skyrmions in chiral flower-like obstacles

Waseda University

EurekAlert!

Phys.org/Physics News


icon 2023.11.28
A farewell party was held for two exchange Ph.D students, Lan Bo and Javier Vélez, at Shara (酒洛), Takadanobaba.
[Photo1], [Photo2]

icon 2023.11.24
Yusuke Miyajima(D2) gave a poster presentation in a conference (第17回物性科学領域横断研究会)[web] held in November 24,25 at Nagoya Institute of Technology[photo].

Title: Machine learning detection of phase transitions in two-dimensional spin models: the second-order transitions and the Berezinskii-Kosterlitz-Thouless transitions
Speaker: Yusuke Miyajima

icon 2023.11.23
The following paper was published in Advanced Materials. In this work, we achieved and demonstrated controlled creation of several kinds of topological magnetic structures in the chiral magnet Fe0.5Co0.5Ge, including meron-antimeron pairs and bimerons, transformation from skyrmions to bimerons, and current-induced splitting and aggregation of bimerons, in a joint experimental and theoretical study. This achievement adds an novel important insight to the study of manipulation of topological magnetism with external fields.

Xiuzhen Yu, Naoya Kanazawa, Xichao Zhang, Yoshio Takahashi, Konstantin V. Iakoubovskii, Kiyomi Nakajima, Toshiaki Tanigaki, Masahito Mochizuki, Yoshinori Tokura
Advanced Materials 36, 2306441/1-9 (2023).

題名: Spontaneous Vortex-Antivortex Pairs And Their Topological Transitions in A Chiral-Lattice Magnet
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icon 2023.11.21
Risako Kikuchi (Nagoya University) gave a seminar talk.
Date: 2023.11.21(Tue.) 13:30
Place: Bldg. 55N, Nishi-Waseda campus, Waseda university
Title: Quantum transport phenomena of spin-1 fermions
Speaker: Risako Kikuchi (Nagoya University, Ph.D student)
icon 2023.11.15
Prof. Shinichiro Seki (University of Tokyo) gave a seminar talk.
Date: 2023.11.15 (Wed.) 15:30
Place: Bldg. 55N, Nishi-Waseda campus, Waseda university
Title: Emergent physical phenomena exhibited by topological magnetism
Speaker: Shinichiro Seki (University of Tokyo)
icon 2023.11.14
Yusuke Miyajima(D2) gave a poster presentation in the international conference on MACHINE LEARNING PHYSICS[web] held in November 13-18 at Yukawa Institute for Theoretical Physics, Kyoto University.

Title: Machine-learning detection of the Berezinskii-Kosterlitz-Thouless transition and the second-order transition in two-dimensional spin models
Presenter: Yusuke Miyajima

icon 2023.11.14
Prof. Naoya Kanazawa (University of Tokyo) gave a seminar talk.
Date: 2023.11.14 (Tue.) 15:30
Place: Bldg. 55N, Nishi-Waseda campus, Waseda university+Zoom (hybrid)
Title: Topology of Electronic and Spin States in Chiral Crystals: Focusing on Emergent Monopoles in MnGe and Ferromagnetic Surface States in FeSi
Speaker: Naoya Kanazawa (University of Tokyo)
icon 2023.11.14
Yusuke Miyajima(D3)will give a poster presentation in the international conference on MACHINE LEARNING PHYSICS [web]) held at Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto, Japan.

Title:Machine-learning detection of the Berezinskii-Kosterlitz-Thouless transition and the second-order transition in two-dimensional spin models
Speaker:Yusuke Miyajima

icon 2023.11.13
Javier Vélez will give the following seminar talk[abstract].
Date&Time:2023/11/13, 14:00-
Place:Bldg. 55N(North Tower), 2nd floor, Department meeting room, Nishi-Waseda campus, Waseda University
Title:Relativistic Dynamics of Antiferromagnetic Domain Walls: Route to Chaos
Speaker:Javier Vélez(Universidad Del Pais Vasco, Spain・PhD student)
icon 2023.11.08
The following paper has been published in Scientific Reports. In this paper, by performing numerical simulations, we demonstrate that reservoir computing based on spin waves propagating in a skyrmion lattice confined in a thin-plate magnet possesses high capability of handwritten digit recognition. We obtain a high recognition rate of more than 88%, higher by about 10% than a baseline taken as the echo state network model.

Mu-Kun Lee, Masahito Mochizuki
Scientific Reports 13, 19423 (2023).

Title:Handwritten digit recognition by spin waves in a Skyrmion reservoir
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icon 2023.11.02
A visiting Ph.D student from Universidad del Pais Vasco (Spain), Javier Antonio Velez Simanca, joined our group. He will stay for a month [Member].

icon 2023.10.24
The following paper has been published in Physical Review B. In this paper, the fluid behaviors of flowing skyrmion particles driven by electric current in a pipe channel are investigated by micromagnetic simulations. We discovered sevela interesting aspects peculiar to the skyrmion flow such as laminar flow, transiently disordered dynamics, dynamical formation and transition of lattice structures, their compression toward the channel edge and so on.

Xichao Zhang, Jing Xia, Oleg A. Tretiakov, Motohiko Ezawa, Guoping Zhao, Yan Zhou, Xiaoxi Liu, Masahito Mochizuki
Phys. Rev. B 108, 144428/1-14 (2023).

Title:Laminar and Quasi-Turbulent Dynamics of a Magnetic Skyrmion Pipe Flow
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icon 2023.09.28
Xichao Zhang (張渓超, PD・Research assistant professor) received the MSJ Distinguished Paper Award from Magnetic Society of Japan.

Title: Current-Induced Helicity Switching of Frustrated Skyrmions on a Square-Grid Obstacle Pattern
Authors: X. Zhang, J. Xia, O. A. Tretiakov, H. T. Diep, G. Zhao, J. Yang, Y. Zhou, M. Ezawa, and X. Liu
Journal Info: J. Magn. Soc. Jpn., 47, pp.20-27 (2023).

icon 2023.09.20
The following oral presentation was given by our group member in The 84th Japanese Society of Applied Physics (JSAP) Autumn meeting 2023 (Kumamoto-jo castle Hall, Kumamoto, Japan)

Numb.: 20a-A303-4
Title: Proposal of a mathematical model of amoeba-inspired combinatorial optimization machines for physical inplemantations (in Japanese)
Speakers: Yusuke Miyajima, Masahito Mochizuki

icon 2023.09.15
The following paper has been published online in Advanced Materials. In this paper, by collaboration of experiment and theory, we demonstrated on-demand creations of multiple topological magnetic states such as pairs of meron and antimeron and bimerons (meron pairs), mutual transformation between skyrmions and bimerons, current-induced proliferation of bimerons.

Xiuzhen Yu, Naoya Kanazawa, Xichao Zhang, Yoshio Takahashi, Konstantin V. Iakoubovskii, Kiyomi Nakajima, Toshiaki Tanigaki, Masahito Mochizuki, Yoshinori Tokura
Advanced Materials adma.202306441 (2023).

題名:Spontaneous Vortex-Antivortex Pairs And Their Topological Transitions in A Chiral-Lattice Magnet
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icon 2023.09.16-19
The following oral presentations were given by our group members in The Physical Society of Japan (JPS) 2023 Annual meeting (Aobayama・Kawauchi Campuses, Tohoku University, Sendai, Japan)

Numb.: 17aB102-8
Title: Theoretical study of helical magnetic engineering in chiral magnetic materials (in Japanese)
Speakers: Masaki Tanabe, Masahito Mochizuki

Numb.: 18aC200-5
Title: Topological magnons in the quadruple-Q magnetic hedgehog lattices (in Japanese)
Speakers: Rintaro Eto, Masahito Mochizuki

Numb.: 16pB202-11
Title: Proposal of a computational model of amoeba-inspired combinatorial optimization machines:Towards physical implementations (in Japanese)
Speakers: Yusuke Miyajima, Masahito Mochizuki

icon 2023.08.24
Prof. Cyrill B. Muratov (Universitá di Pisa, Italy) and Dr. Anne Bernand-Mantel(Université de Toulouse, France) visited us in Waseda University. Dr. Anne Bernand-Mantel gave a seminar lecture[Abstract], [Album].

Date:2023.08.24(Thu.) 10:15-
Title:Theory of magnetic field-stabilized compact skyrmions in thin film ferromagnets
Speaker:Dr. Anne Bernand-Mantel(Université de Toulouse, LPCNO, France)
icon 2023.08.21-22
The following presentations were given by our group members in the workshop on the strongly correlated electron systems [web] held in August 21-22 at Sakata-Hirata Hall, Higashiyama campus, Nagoya University, Japan.

[Invited talk]
Title:Optical responses and photo-induced phase transitions in spin-charge coupled magnets (in Japanese)
Speaker: Masahito Mochizuki

[Poster presentation]
Title: Machine-Learning detection of the Berezinskii-Kosterlitz-Thouless transitions and second-order transitions in two-dimensional spin models (in Japanese)
Speaker: Yusuke Miyajima (D2)

Title: Weyl nodal magnons in magnetic 4Q hedgehog lattices (in Japanese)
Speaker: Rintaro Eto (D1)
icon 2023.08.09
The following paper was published in Physical Review B. In this paper, we demonstrate using micromagnetics simulations that the configurations of magnetic domains in the notched ferromagnetic nanotrack can be switched between a head-to-head state and a tail-to-tail state in a reversible manner by application of magnetic-field pulses even without reversing the direction of the magnetic field.

Xichao Zhang, Jing Xia, Oleg A. Tretiakov, Guoping Zhao, Yan Zhou, Masahito Mochizuki, Xiaoxi Liu, Motohiko Ezawa
Phys. Rev. B 108, 064410/1-11 (2023).

Title:Reversible magnetic domain reorientation induced by magnetic field pulses of fixed direction
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icon 2023.07.25
Rintaro Eto(D1)gave a poster presentation at the 11th International Symposium on Metallic Multilayers (MML2023) held in July 24-28 at Korea University in Seoul, Korea.

Title:Spin-charge Decoupling in the Low-energy Excitations of Skyrmion Crystals in Kondo-lattice Magnets
Authors:R. Eto, M. Mochizuki

icon 2023.07.19
Prof. Mochizuki gave an invited talk at the 13th International Conference on Metamaterials, Photonic Crystals and Plasmonics (META2023) held in July 18-21 at Ecole Nationale Supérieure d'Arts et Métiers (ENSAM), Paris Campus in Paris, France.

Title:Creation, Manipulation and Switching of Topological Magnetisms in Spin-Charge Coupled Magnets

icon 2023.07.13
The following paper was published in Journal of the Physical Society of Japan. In this paper, we theoretically propose and demonstrate a physical mechanism for the emergence of complex spin textures, including topological ones, with spatial structure of local polarizations in magnets with spatial inversion symmetry, through the spin-lattice coupling via the Dzyaloshinskii-Moriya interactions as well as electric and magnetic dipole interactions.

Tatsuki Muto, Masahito Mochizuki
Journal of the Physical Society of Japan 92, 084704/1-7 (2023).

Title:Theory of Magnetic Vortex Crystals Induced by Electric Dipole Interactions
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icon 2023.07.07
Prof. Mochizuki gave an invited talk at the 4th International Symposium on Negative Thermal Expansion and Related Materials (ISNTE-4) held in July 5-7 at Giove Convention Centre of the Best Western Plus Hotel Galileo in Padova, Italy.

Title:Theory of magnetism-induced negative thermal expansion in inverse perovskite antiferromagnets

icon 2023.06.28
The following paper was published in Physical Review B. In this paper, we theoretically propose a method to generate novel topological magnetic structures called skyrmion bags in a nanodisc of chiral magnet by magnetic-field application and local current injection.

Lan Bo, Rongzhi Zhao, Chenglong Hu, Xichao Zhang, Xuefeng Zhang, Masahito Mochizuki
Physical Review B 107, 224431/1-7 (2023).

Title:Controllable creation of skyrmion bags in a ferromagnetic nanodisk
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icon 2023.06.19, 2023.06.20
Prof. Mochizuki and R. Eto (PhD student, D1) gave oral presentations at the 7th edition of the Sol-SkyMag International Conference (Sol-SkyMag2023) held in June 19-23 at Carlos Santamaría Library Conference Hall in San Sebastian (Gizpoka), Spain [Album].

2023.06.19
Title:Goldstone excitations with spin-charge separation in skyrmion crystals in Kondo-lattice systems
Speaker:Rintaro Eto

2023.06.20
Title:Thermoelectric effect of magnetic skyrmions
Speaker:Masahito Mochizuki


icon 2023.06.12
Prof. Oleg Tretiakov(University of New South Wales (UNSW), Sydney) visited our group [Album].

icon 2023.06.07
Prof. Mochizuki gave an invited talk at the 9th International Conference on Anntenas and Electromagnetic Systems (AES2023) held in June 4-8 at Palacio de Congresos in Torremolinos, Spain.

Title:Electromagnon Excitations and Microwave/Optical Device Functions in Multiferroic Materials

icon 2023.05.31
Prof. Dr. Mathias Kläui (Johannes Gutenberg University Mainz, Germany) gave a seminar talk[Abstract], [Album].
Date:2023.05.31(Wed.) 15:15
Place:Bldg. 55N(North Tower), 1st floor, 2nd Conference Room, Nishi-Waseda campus, Waseda University
Title:Skyrmions in Spin-Orbitronics and Orbitronics – novel science and applications in memory & non-conventional computing
Speaker:Prof. Dr. Mathias Kläui(Johannes Gutenberg-Universität Mainz, Germany)
icon 2023.05.31
A mini workshop was organized to coincide with Professor Dr. Mathias Kläui's visit. Prof. Dr. Mathias Kläui (Johannes Gutenberg University Mainz, Germany) gave a seminar talk (Special Lecture) [Program], [Album].
Date:2023.05.31(Wed.) 11:30-
Place:Bldg. 55N(North Tower), 1st floor, 2nd Conference Room, Nishi-Waseda campus, Waseda University
icon 2023.05.23

The following book (in Japanese) was published from NTS publishers, Japan. Prof. Mochizuki provided a section contribution about the skyrmions [web],[pamphlet]

Book title: Spintronics Handbook ―Fundamentals and Applications―(760 pages)

ISBN 978-4-86043-842-5, e-Book ISBN 978-4-86043-843-2
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2023.05.18
Mu-Kun Lee (Lecturer) gave an oral presentation at IEEE INTERMAG 2023 [web] held in May 15-19 at Sendai International Center in Sendai, Japan.
Title:Reservoir Computing with Spin Waves in a Skyrmion Crystal
Authors:Mu-Kun Lee, Masahito Mochizuki

icon 2023.05.11
Le Zhao (Ph.D student, Tsinghua University, China) gave a seminar talk in our group.
Date: 2023.05.11 (Thur), 14:00
Speaker: Le Zhao(Tsinghua University, China)
Title: Skyrmion Research
Place:Bldg. 55N(North Tower), 1st floor, 2nd Conference Room, Nishi-Waseda campus, Waseda University


icon 2023.05.06
Prof. Mochizuki gave an invited talk at the 8th International Conference on Superconductivity and Magnetism (ICSM2023) held in May 4-11 at Liberty Hotels Lykia in Ölüdeniz, Turkey.

Title:Dynamical Switching, Creation and Manipulation of Topo Magnetism in Spin-Charge Coupled Magnets

icon 2023.04.17
The following paper was published in Physical Review B. In this paper, we propose versatile and powerful machine learning methods for detecting the Berezinskii-Kosterlitz-Thouless transition and the second-order transition in the XXZ model and demonstrate their efficiencies. The XXZ model has three-dimensional spin vectors, which makes it much more difficult to detect phase transitions than the XY and clock models with two-dimensional spin vectors. The proposed methods, called ``temperature identification method" and ``phase classification method", can detect phase transitions in the XXZ model with minimal prior knowledge of the model and prior processing of the data.

Y. Miyajima and M. Mochizuki
Physical Review B 107, 134420/1-16 (2023).

Title:Machine-learning detection of the Berezinskii-Kosterlitz-Thouless transition and the second-order phase transition in XXZ models
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icon 2023.04.01
Ryui KANEKO (Research Associate Professor) and Yuya OMINATO(Lecturer at WIAS)joined our group. Tatsuya IGUCHI and Ryo HAMANO also joined as batchelor students. Mu-Kun LI has been promoted to a lecturer.[Member]

icon 2023.03.31
Jean-Baptiste MORÉE (Research Lecturer) and Michael Thobias SCHMID (Research Lecturer) have moved our from our group.

icon 2023.03.26
Two students, Yuto Uwabo and Rintaro Eto, have completed their master's degree in the Department of Physics and Applied Physics at Waseda University[Album].

icon 2023.03.26
Two students, Masaki Tanabe and Hirotaka Yano, graduated from the Department of Physics and the Department of Applied Physics, respectively, at Waseda University[Album].

icon 2023.03.26
Rintaro Eto (M2) was selected as a winner of the Koizumi Prize for master's thesis in the Department of Physics and Applied Physics.
[Photo1], [Photo2]

icon 2023.03.26
Rintaro Eto (M2) received the 64th Azusa Ono Memorial Prize for Academic Achievement[Album].

The Azusa Ono Memorial Prize is a student prize established by Waseda University, and is the most prestigious prize among the prizes awarded to students. It was established in 1958 to commemorate the achievements of Azusa Ono, who was a political scientist and worked with Shigenobu Okuma to establish the Tokyo Senmon Gakko, the predecessor of Waseda University.

【Achievement eligible for the award】
R. Eto, R. Pohle, and M. Mochizuki, Phys. Rev. Lett. 129, 017201/1-7 (2022).
Low-Energy Excitations of Skyrmion Crystals in a Centrosymmetric Kondo-Lattice Magnet: Decoupled Spin-Charge Excitations and Nonreciprocity

icon 2023.03.22-25
The following oral presentations were given by our group members in The Physical Society of Japan (JPS) 2023 Spring meeting (Online)
Numb.: 22aC1-3
Title: Machine-Learning Detection of the phase transitions:The second-order transition and the Berezinskii-Kosterlitz-Thouless transition in the two-dimensional classical XXZ models (in Japanese)
Speakers: Yusuke Miyajima, Masahito Mochizuki

Numb.: 23aC2-10
Title: Reservoir Computing with Spin Waves in a Skyrmion Crystal (in English)
Speakers: Mu-Kun Lee, Masahito Mochizuki

Numb.: 23aC2-11
Title: Thiele analysis of the current-induced skyrmion creation and dynamics with the spin-orbit torques (in Japanese)
Speakers: Yuto Uwabo, Masahito Mochizuki

Numb.: 23pE2-5
Title: Theoretical study on photoinduced topological phases in a ferrimagnetism-induced Dirac half-metallic state: Analysis of the periodic Anderson model (in Japanese)
Speakers: Rintaro Eto, Masahito Mochizuki

Numb.: 24pE1-3
Title: Theoretical studies on the photoinduced half-valley metallic phase in α-type organic salt (in Japanese)
Speakers: Keisuke Kitayama, Masao Ogata, Yasuhiro Tanaka, Masahito Mochizuki

icon 2023.03.17
A farewell party was held at Rihga Royal Hotel, Kanshi-so[Album].


icon 2023.03.15-18
The following oral presentation were given by our group members in The 70th JSAP (The Japan Society of Applied Physics) Spring Meeting 2023 (Yotsuya Campus, Sophia University + Online)
Numb.: 16a-D419-9
Title: Theoretical study on controlled creations and dynamics of magnetic skyrmions with the spin-orbit torques (in Japanese)
Speakers: Yuto Uwabo, Masahito Mochizuki

icon 2023.03.13
The following paper was published in a Letter section of Physical Review B. In this paper, we theoretically predicted and demonstrated that by irradiating a skyrmion crystal confined in a circular disk with light or electron beams, we can generate a DC electromotive force in the radial direction from a steady rotational motion in the presence of temperature gradient introduced by the irradiation. This is the world's first proposal of the thermoelectric function of magnetic skyrmions.

J. Matsuki and M. Mochizuki
Physical Review B 107, L100408 (2023).

Title:Thermoelectric effect of a skyrmion crystal confined in a magnetic disk
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icon 2023.03.05-10
The following oral presentations were given by our group members in APS March Meeting 2023 (Las Vegas, Nevada, USA).
Numb.: M44.00005 (9:36 AM–9:48 AM, March 8 (Wed), 2023, Room 316)
Title: Dynamical switching of magentic topology in microwave-driven itinerant magnet
Speakers: Rintaro Eto, Masahito Mochizuki

Numb.: W54.00006 (4:24 PM–4:36 PM, March 9 (Thu), 2023, Room 306)
Title: Reservoir Computing with Spin Waves in a Skyrmion Crystal
Speakers: Mu-Kun Li, Masahito Mochizuki

icon 2023.02.19
The following paper was published in npj Quantum Materials. In this paper, we studied the electromagnon excitations in a multiferroic material CuO in collaboration with an experimental group in France. This material exhibits a multiferroic phase near the room temperature. We constructed its microscopic spin model that can quantitatively reproduce the observed multi-step magnetoelectric phase transitions. Using this model, we succeeded in fully reproducing the experimental far-infrared spectra of electromagnon excitations in the multiferroic phase at finite temperatures.

M. Verseils, P. Hemme, D. Bounoua, R. Cervasio, J-B. Brubach, S. Houver, Y. Gallais, A. Sacuto, D. Colson, T. Iijima, M. Mochizuki, P. Roy and M. Cazayous
npj Quantum Materials 8, 11 (2023).

Title:Stabilizing electromagnons in CuO under pressure
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icon 2023.02.03
The graduation thesis presentations of the Department of Applied Physics and the Department of Physics were held. Two students from our group, Masaki Tanabe and Hirotaka Yano, gave presentations.

【Bachelor Thesis Titles】
Masaki Tanabe ``Theory of helimagnetism engineering in chiral magnets"
Hirotaka Yano ``Theoretical study on the magnetic phases in a skyrmionic material with a polar tetragonal crystal structure"

icon 2023.02.04
The master's thesis presentations of the Department of Physics and Applied Physics were held. Two students from our group, Yuto Uwabo and Rintaro Eto, gave presentations.

【Mater's Thesis Titles】
Yuto Uwabo ``Theoretical study on the creation and motion of skyrmions driven by the spin-orbit torque"
Rintaro Eto ``Theory of low-energy excitations and photocontrol of topological spin textures in spin-charge coupled magnets"

icon 2023.01.27
Prof. Mochizuki gave an invited talk at the workshop held on January 27 at Tokyo Satellite Campus of Nagaoka University of Technology.

Title:Reservoir-type information processing device utilizing spin-wave propagation in a skyrmion crystal (in Japanese)

icon 2023.01.17
Yusuke Miyajima (PhD student) gave an oral presentation at 2023 Annual Meeting of the Physical Society of Taiwan (TPS2023) held in Taiwan (Jan. 16-18, 2023).

Title: Proposal of a machine learning method for detection of the Berezinskii-Kosterlitz-Thouless transitions in the q-state clock models

icon 2023.01.11
Xichao ZHANG has joined our lab. as a postdoc/research lecturer [Members]. He will work on the JST, CREST research project Creation of a new topological magnetic science for Beyond Skyrmion".

icon 2022.12.24
Prof. Mochizuki gave an invited talk at a workshop about new trends in the chiral materials science held in ISSP, the University of Tokyo (Dec.22-24, 2022).

Title: Chiralities and dynamics in the multiferroics (in Japanese)

icon 2022.12.22
Keisuke Kitayama (Former student member) gave an oral presentation at a winter school for young researchers on organic materials [web] held at Okazaki Conference Center in National Institutes of Natural Sciences (NINS), Okazaki, Aichi, Japan (December 22-23, 2022).

Title: Theoretical studies of photoinduced topological phase transitions in organic salt α-(BEDT-TTF)2I3 (in Japanese)

icon 2022.12.19
BO Lan has joined our lab. as a research student [Members]. He is a third-year Ph.D student in the Northeastern university in China. He will stay in our lab for a year as a postgraduate student funded by China Scholarship Council.

icon 2022.12.07
Li Mu-Kun (Postdoc・Research Lecturer) gave an oral presentation at an international workshop ``The Workshop on Innovative Nanoscale Devices and Systems (WINDS2022)" held on the Island of Kaua'i, Hawaii (December 4-9, 2022).

Title: Microwave-Driven Phenomena of Magnetic Skyrmions

icon 2022.11.15
Keisuke Kitayama (Former student member) gave a poster presentation at the YIPQS long-term and Nishinomiya-Yukawa memorial workshop ``Novel Quantum States in Condensed Matter 2022" (NQS2022) held at Yukawa Institute for Theoretical Physics (YITP), Kyoto university, Kyoto, Japan (Oct. 31-Dec. 2, 2022).

Title: Theoretical studies of photoinduced topological phase transitions in organic salt α-(BEDT-TTF)2I3

icon 2022.11.02
Prof. Mochizuki gave an oral presentation at an international workshop ``The 67th Annual Conference on Magnetism and Magnetic Materials (MMM2022)" held in Hyatt Regency Minneapolis, MN, USA (Oct.31-Nov.4, 2022).

Title: Microwave-Driven Phenomena of Magnetic Skyrmions

icon 2022.09.29
Keisuke Kitayama (Former student member) gave an oral presentation at an international workshop The 14th International Symposium on Crystalline Organic Metals, Superconductors and Magnets (ISCOM2022)" held in Le Pouliguen, France (September 25-30, 2022).

Title: Theoretical studies of photoinduced topological phase transitions in organic salt α-(BEDT-TTF)2I3

icon 2021.09.28
Rintaro Eto (second-year master's student) has been selected as a JSPS Research Fellow DC1 for the coming year.

icon 2021.09.26
The following paper has been published in Journal of the Physical Society of Japan. In this paper, we theoretically predicted possible occurrence of a new-type photoinduced topological phase transition in the organic salt α-(BEDT-TTF)2I3 irradiated by elliptically polarized laser light. We found that a nonequilibrium phase transition from the Floquet Chern-insulator phase to the Floquet normal-insulator phase takes place accompanied by collapse and vanishing of the Dirac points with the same topological magnetic charges when the angle that the elliptical polarization axis makes with the crystallographic axis is 45$^\circ$.

K. Kitayama, M. Ogata, M. Mochizuki, and Y. Tanaka,
J. Phys. Soc. Jpn. 91, 104704/1-8 (2021).

題名:Predicted novel type of photoinduced topological phase transition accompanied by collision and collapse of Dirac-cone pair in organic salt α-(BEDT-TTF)2I3
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icon 2022.09.12-15
The following presentations have been given by our group members in 2022 JPS Autumn meeting (Tokyo Institute of Technology, Ookayama Campus)

Numb.: 12aW241-1
Title: Theoretical study on the photoinduced topological phases in the ferrimagnetism-induced Dirac electron state
Speakers: Rintaro Eto, M. Mochizuki

Numb.: 13aW331-12
Title: Melting of charge order and topological phase transition in organic conductor α-(BEDT-TTF)2I3 irradiated with circularly polarized light
Speakers: Yasuhiro Tanaka, M. Mochizuki

Numb.: 13aW641-2
Title: Theoretical study of magnetic vortex crystals induced by electric dipole interactions
Speakers: Tatsuki Muto, M. Mochizuki

Numb.: 13aW641-5
Title: Theoretical study of magnetic phase transitions and electromagnon excitations in multiferroic CuO
Speakers: Takaaki Iijima, M. Mochizuki

Numb.: 13pW641-2
Title: Theoretical study on creations and manipulations of magnetic skyrmions with the spin-orbit torque
Speakers: Yuto Uwabo, M. Mochizuki

Numb.: 14pW541-6
Title: Theoretical study on the collective spin excitations of quadruple-Q magnetic hedgehog lattices
Speakers: Rintaro Eto, M. Mochizuki

Numb.: 14pW641-7
Title: Theoretical study on thermoelectric effect of magnetic skyrmion crystal confined in a disk-shaped system
Speakers: Junnosuke Matsuki, M. Mochizuki

icon 2022.09.10
The following symposium talk has been given by Mochizuki in the Symposium on ``Spin quantum phenomena driven by light and terahertz" in 2022 JPS Autumn meeting (Tokyo Institute of Technology, Ookayama Campus)

Title: Theory of optical manipulations of magnetisms (10aS2-3)

icon 2022.08.22
Keisuke Kitayama (Former student member) gave an oral presentation at an international workshop ``The 29th International Conference on Low Temperature Physics (LT29)" held at Sapporo Convention Center, Sapporo, Hokkaido, Japan (August 18-24, 2022).

Title: Theoretical studies of photoinduced topological phase transitions in organic salt α-(BEDT-TTF)2I3

icon 2022.07.29
The following paper has been published in Physical Review Applied. In this paper, we theoretically demonstrated that spin-waves propagating in a magnetic skyrmion crystal confined in thin-plate magnets have high potential for application to reservoir-computing devices. We numerically examined several characteristics required for reservoir computings for the skyrmion spin-wave reservoir, i.e., the generalization ability, the short-term memory, and the nonlinearlity by imposing the duration estimate task, the short-term memory task, and the parity check task, respectively, and revealed that the skyrmion spin-wave reservoirs possess high figures of merits for these characteristics. This paper was selected as an Editors' Suggestion.

M-K. Lee, and M. Mochizuki,
Phys. Rev. Applied 18, 014074 (2022).Editors' Suggestion

Title: Reservoir Computing with Spin Waves in a Skyrmion Crystal
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icon 2022.07.26
A visiting Ph.D student from Ibaraki University, Keisuke Masuda, joined our group. He will stay for a month [Member].

icon 2022.07.21
An article (in Japanese) about our theoretical studies on the photoinduced phase transitions in α-(BEDT-TTF)2I3 has been published in Kotaibutsuri journal.

M. Mochizuki, K. Kitayama, Y. Tanaka, M. Ogata
Kotaibutsuri Vol. 57, Issue 7 (2022.07.「Topics」) pp. 1(397)-13(409).

Title: Theoretical studies on the photoinduced topological phase transitions in an organic salt α-(BEDT-TTF)2I3

icon 2022.07.21
The following invited talk has been given by Mochizuki in the 12th International Conference on Metamaterials, Photonic Crystals and Plasmonics (META2022, Spain, Torremolinos).

Title: Dynamical Magnetic Phase Transitions in Spin-Charge Coupled Systems

icon 2022.07.18
The following paper has been published in Physical Review Letters. In this paper, we theoretically studied the photoinduced phase transitions in a typical strongly correlated Dirac electron system α-(BEDT-TTF)2I3 irradiated with circularly polarized light. By analyzing an extended Hubbard model with on-site and inter-site Coulomb repulsive interactions using a newly developed theoretical framework which combines real-time dynamics simulations and the Foquet theory, we revealed successive photoinduced phase transitions from the ground-state charge-ordered insulator via the Dirac semimetal to the Chern insulator and its microscopic mechanisms associated with dynamical variations of electronic structures.

Y. Tanaka, and M. Mochizuki,
Phys. Rev. Lett. 129, 047402/1-6 (2022).

Title: Dynamical phase transitions in the photodriven charge-ordered Dirac-electron system
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icon 2022.07.13
The following invited talk has been given by Mochizuki in the 24th International Colloquium on Magnetic Films and Surfaces (ICMFS-2022, OIST, Okinawa, Japan).

Title: Dynamical Phenomena of Magnetic Skyrmions

icon 2022.06.28
The following paper has been published in Physical Review Letters. In this paper, we numerically studied low-energy excitations of magnetic skyrmion crystals in the Kondo-lattice model on a triangular lattice with spatial inversion symmetry and discovered two Goldstone modes associated with charge and spin degrees of freedom and their perfect segregation. Our finding indicates that the charges and spins can be excited separately and selectively in the skyrmion crystals stabilized by interactions mediated by conduction electrons in centrosymmetric magnets.

R. Eto, R. Pohle, and M. Mochizuki,
Phys. Rev. Lett. 129, 017201/1-7 (2022).

Title: Low-Energy Excitations of Skyrmion Crystals in a Centrosymmetric Kondo-Lattice Magnet: Decoupled Spin-Charge Excitations and Nonreciprocity




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icon 2021.09.17.
Condensed-Matter Theory Seminar (in-person).
Date&Time: 2022.06.17 (Fri.) 14:00
Speaker: Prof. Oleg Tretiakov((University of New South Wales (UNSW), Sydney)
Title: Nucleation and dynamics of magnetic solitons in topological materials


icon 2022.04.19
The following paper has been published in Physical Review B. In this paper, we theoretically predict a possible photoinduced magnetic phase transition from the ferromagnetism to the 120-degree spin order in the Kondo-lattice model on a triangular lattice. A pseudo half-filled electronic structure turns out to stabilize the 120-degree order, which is realized via electron excitations, dynamical localizations, gap opening, relaxations, and reconstruction of the electronic structure under irradiation with light. This work demonstrates that the light irradiation can induce a noncollinear magnetic state as a nonequilibrium steady phase via the general mechanism.

T. Inoue, and M. Mochizuki, Phys. Rev. B 105, 144422 (2022).

Photoinduced 120-degree spin order in the Kondo-lattice model on a triangular lattice
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icon 2022.03.18
The following symposium talk has been given by Mochizuki in a symbosium of the 77th JPS annual meeting.

Numb.: 18pS11-6
Title: Photoinduced topological phase transitions in the α-type organic salt (Theory)

icon 2021.12.22-23
The following invited talk has been given by Mochizuki in the international conference on "Frustration, Topology and Spin Textures" (Kobe, Japan).

Title: Dynamical manipulations of topological magnetism with light and microwave electromagnetic fields

icon 2021.12.22-23
The following poster presentations has been given by our group in the international workshop on "Frustration, Topology and Spin Textures" (Kobe, Japan).

Title: Theory of optical spin-polarization induction in Rashba spin-orbit electron systems
Presenters: Yasuhiro Tanaka, Takashi Inoue, Masahito Mochizuki

Title: Photoinduced 120-degree spin order and Z2 vortices in the Kondo-lattice model on a triangular lattice
Presenters: Takashi Inoue, Masahito Mochizuki

Title: Machine learning detection of multiple phase transitions including BKT transition in the q-state clock models
Presenters: Yusuke Miyajima, Masahito Mochizuki

Title: Theoretical Exploration of Magnetism-Induced Negative Thermal Expansion in Honeycomb-Lattice Antiferromagnets
Presenters: Yuto Uwabo, Masahito Mochizuki

Title: Spin and Charge Excitations of Skyrmion Crystals in Itinerant Magnet
Presenters: Rintaro Eto, Rico Pohle, Masahito Mochizuki


icon 2021.12.15
Mochizuki gave an invited talk in RIKEN Institute.

Title: Reservoir computing with spin waves in magnetic skyrmion crystal

icon 2021.12.01-02
Our members, Y. Tanaka, M. Naka, and K. Kitayama, gave presentations in the ISSP workshop on novel materials and phenomena of orgaic compounds (Kashiwa, Japan).

icon 2021.10.30
Rico Pohle has moved to Prof. Motome's group in Univ. of Tokyo.

icon 2021.10.20
The following invited talk has been given by Mochizuki in the international conference on ``Condensed Matter Physics (CONMAT2021)" (online).

Title: Theory of Magnetism-Induced Negative Thermal Expansion in Inverse Perovskite Antiferromagnets

icon 2021.09.27
The following paper has been published in Physical Review B. In this paper, we theoretically predict and reveal possible magnetic-topology switching among skyrmion crystals with different topological numbers and nontopological magnesitms by irradiating centrosymmetric Kondo-lattice magnets on a triangular lattice with circularly polarized microwave magnetic fields. In transient processes of these microwave-induced topology switchings, we observe several distinct behaviors of dynamical phase transitions as well as emergence of peculiar topological magnetisms called meron crystals charcterized by skyrmion numbers of half integers.

R. Eto, and M. Mochizuki, Phys. Rev. B 90, 104425 (2021).

Title: Dynamical switching of magnetic topology in microwave-driven itinerant magnet
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icon 2021.09.24
The following paper has been published in Journal of the Physical Society of Japan. In this paper, we theoretically propose possible realization of the negative thermal expansion in the honeycomb-lattice antiferromagnets composed of edge-sharing MX6 octahedra (M and X represent transition-metal ions and ligand ions, respectively). In contrast to normal materials, crystal volumes of these kinds of magnets are expected to expand upon cooling, which is triggered by the antiferromagnetic phase transition.

Y. Uwabo, and M. Mochizuki, J. Phys. Soc. Jpn. 90, 104712 (2021).

Title: Proposed Negative Thermal Expansion in Honeycomb-Lattice Antiferromagnets
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icon 2021.09.20-23
The following presentations have been given by our members in 2021 JPS Autumn meeting (online)

Numb.: 20aC1-4
Title: Theoreticalstudyonthedynamicsofmagnetictexturesinitineranthelicalmagnets
Speakers: R. Eto, Rico Pohle, M. Mochizuki

Numb.: 21pE1-7
Title: Topological state induced by circularly polarized light in organic conductor
Speakers: Y. Tanaka, M. Mochizuki

Numb.: 22aC1-5
Title: Theoretical Exploration of Negative Thermal Expansion in Honeycomb Lattice Transition Metal Compounds
Speakers: Y. Uwabo, M. Mochizuki

Numb.: 22pL4-3
Title: Detection of the Kosterlitz-Thouless transitions by machine learning
Speakers: Y. Miyajima, Y. Murata, Y. Tanaka, M. Mochizuki

Numb.: 23pH3-5
Title: Theoretical study of the Dirac-point pair annihilation and topological phase transitions in the α-type organic salt induced by elliptically polarized light
Speakers: K. Kitayama, Y. Tanaka, M. Ogata, M. Mochizuki

icon 2021.09.17.
The 5th Condensed-Matter Theory Seminar (online) in FY2021.

Date&Time: 2021.09.17 (Thu.) 16:00
Speaker: Lan Bo (Northeastern University, P. R. China)
Title: Micromagnetic Behaviors of Magnetic Topological Solitons [Abstract]


icon 2021.09.15
The following paper has been published in Journal of the Physical Society of Japan. In this paper, we reveal entire behaviors of photoinduced topological phase transitions in the organic salt α-(BEDT-TTF)2I3 with a pair of tilted Dirac-cone dispersions theoretically using the Floquet thoery. Irradiation by elliptically polarized light give rise to quite rich nonequilibrium phase diagrams containing photoinduced Chern insulator phases. (Selected as Editors' Choice)

K. Kitayama, Y. Tanaka, M. Ogata, and M. Mochizuki
J. Phys. Soc. Jpn. 90, 104705 (2021).Editors' Choice

Title: Floquet theory of photoinduced topological phase transitions in the organic salt α-(BEDT-TTF)2I3 irradiated with elliptically polarized light
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icon 2021.08.16
The following paper has been published in Physical Review B. In this paper, we theoretically reveal that irradiation by linearly polarized light can induce a pair annihilation of emergent topological magnetic charges with opposite signs in the momentum space of an organic salt α-(BEDT-TTF)2I3, in which a pair of tilted Dirac-cone bands are slightly gapped due to weak charge dispropotionation. This is a theoretical prediction of monopole-antimonopole pair annihilation of 2D version can be realized by photoirradiation in the momentum space of crystalline materials.

K. Kitayama, M. Mochizuki, Y. Tanaka, and M. Ogata
Phys. Rev. B 104, 075127 (2021).

Title: Predicted photoinduced pair annihilation of emergent magnetic charges in the organic salt α-(BEDT-TTF)2I3 irradiated by linearly polarized light
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icon 2021.08.13
The following paper has been published in Physical Review B. In this paper, we theoretically clarify the real-time dynamics of photoinduced topological phase transitions in an organic salt α-(BEDT-TTF)2I3 with tilted Dirac-cone band dispersions under irradiation with circularly polarized light. It is revealed that spatiotemporal dynamics characterized of different three time scales appear, which are, respectively, governed by the light frequency, the averaged magnitude of gaps at the Dirac points, and the difference of gap amplitudes between the two Dirac points under application of an electric field.

Y. Tanaka and M. Mochizuki,
Phys. Rev. B 104, 085123 (2021).

Title: Real-time dynamics of the photoinduced topological state in organic conductor α-(BEDT-TTF)2I3 under continuous-wave and pulse excitations
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icon 2021.08.11
The following paper has been published in Physical Review B. In this paper, we demonstrate that a machnie learning is capable of detecting successive Berezinskii-Kosterlizt-Thouless transitions in the n-state clock models. Introducing a new correlation function to the heat-map anlyses, we quantitatively determine the BKT transition points.

Y. Miyajima, Y. Murata, Y. Tanaka, and M. Mochizuki,
Phys. Rev. B 104, 075114 (2021).

Title: Machine learning detection of Berezinskii-Kosterlitz-Thouless transitions in q-state clock models
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icon 2021.07.22
The 4th Condensed-Matter Theory Seminar (online) in FY2021.

Date&Time: 2021.07.22 (Thu.) 15:00
Speaker: Rubén M. Otxoa (Hitachi Cambridge Laboratory)
Title: Topological energy release from collision of relativistic antiferromagnetic solitons[Abstract]


icon 2021.07.20
Invited talk in the international conference ``The 11th International Conference on Metamaterials, Photonic Crystals and Plasmonics (META 2021)".

SpeakerM. Mochizuki
Title: Theory of Photoinduced Spin Polarization in Spin-Orbit-Coupled Systems

icon 2021.07.01
Dr. Collins Ashu AKOSA joined our group as a postdoc researcher (project lecturer) of the JST-CREST project.

icon 2021.05.31
Ms. Yoko Takahashi (Secretary) retired.

icon 2021.06.01
The 3rd Condensed-Matter Theory Seminar (online) in FY2021.

Date&Time: 2021.06.01 (Thu.) 16:00
Speaker: Yuya Ominato (KITS, UCAS, P. R. China)
Title: Spin transport phenomena in atomic layer materials [Abstract]


icon 2021.05.26
The 2nd Condensed-Matter Theory Seminar (online) in FY2021.

Date&Time: 2021.05.26 (Wed.) 16:30
Speaker: Atsushi Ono (Tohoku university)
Title: Photoinduced spin-scalar-chiral states in triangular-lattice itinerant magnets [Abstract]


icon 2021.05.25
The 1st KIBAN-A meeting (online).
[Program]

icon 2021.05.24
The 1st Condensed-Matter Theory Seminar (online) in FY2021.

Date&Time: 2021.05.24 (Mon.) 13:30
Speaker: Shunsuke Furuya (Ibaraki university)
Title: DC electric-field controls of superexchange and Dzyaloshinskii-Moriya interactions in Mott insulators [Abstract]


icon 2021.05.18
Rintaro Eto gave a talk on an online seminar in Motome group, Department of Applied Physics, the University of Tokyo.

icon 2021.06.01
The 3rd Condensed-Matter Theory Seminar (online) in FY2021.

Date&Time: 2021.06.01 (Thu.) 16:00
Speaker: Yuya Ominato (KITS, UCAS, P. R. China)
Title: Spin transport phenomena in atomic layer materials [Abstract]


icon 2021.05.26
The 2nd Condensed-Matter Theory Seminar (online) in FY2021.

Date&Time: 2021.05.26 (Wed.) 16:30
Speaker: Atsushi Ono (Tohoku university)
Title: Photoinduced spin-scalar-chiral states in triangular-lattice itinerant magnets [Abstract]


icon 2021.05.25
The 1st KIBAN-A meeting (online). [Program]

icon 2021.05.24
The 1st Condensed-Matter Theory Seminar (online) in FY2021.

Date&Time: 2021.05.24 (Mon.) 13:30
Speaker: Shunsuke Furuya (Ibaraki university)
Title: DC electric-field controls of superexchange and Dzyaloshinskii-Moriya interactions in Mott insulators [Abstract]


icon 2021.05.18
Rintaro Eto (M1 student) gave a talk on an online seminar in Motome group, Department of Applied Physics, the University of Tokyo.