KEIO RESEARCHERS INFORMATION SYSTEM

Career 【 Display / hide 】

Career 【 Display / hide 】

• 2012.04

  -

  2013.03

  The University of Tokyo, 大学院新領域研究科, 日本学術振興会 特別研究員(PD)

• 2013.04

  -

  2015.06

  理化学研究所, 創発物性科学研究センター, 特別研究員

• 2015.07

  -

  2018.06

  The University of Tokyo, Graduate School of Arts and Sciences, 助教

• 2018.07

  -

  2022.06

  Tohoku university, Institute of Materials Research, Assistant professor

• 2019.10

  -

  2023.03

  科学技術振興機構, さきがけ研究員（兼任）

display all >>

Academic Degrees 【 Display / hide 】

Academic Degrees 【 Display / hide 】

• 博士（理学）, Tohoku University, 2012.03

Research Areas 【 Display / hide 】

Research Areas 【 Display / hide 】

• Natural Science / Semiconductors, optical properties of condensed matter and atomic physics

• Natural Science / Magnetism, superconductivity and strongly correlated systems

Research Keywords 【 Display / hide 】

Research Keywords 【 Display / hide 】

• トポロジカル磁気構造

• Nano device

• Acoustics

• マイクロ波光学

• Scanning Microwave Impedance Microscopy

display all >>

Papers 【 Display / hide 】

Papers 【 Display / hide 】

• Current-Induced Sliding Motion in a Helimagnet MnAu2

  Yuta Kimoto, Hidetoshi Masuda, Takeshi Seki, Yoichi Nii, Jun-ichiro Ohe, Yusuke Nambu, Yoshinori Onose

  Physical Review Letters (American Physical Society (APS))  134 ( 5 )  2025.02

  ISSN  0031-9007

  　View Summary

  We found signatures of current-induced sliding motion in helimagnetic MnAu2 thin films. An abrupt change in differential resistivity occurred at a threshold bias current in the helimagnetic state, whereas it was absent in the induced ferromagnetic state. Broadband voltage noise also emerged above the threshold current in the helimagnetic state. Based on the similarity to canonical charge and spin density wave systems, we ascribed the origin of these phenomena to the sliding motion of the helimagnetic structure.
  
  Published by the American Physical Society 2025

  • Access to Document (DOI)

• Band asymmetry-driven nonreciprocal electronic transport in a helimagnetic semimetal a-EuP3

  Alex Hiro Mayo, Darius-Alexandru Deaconu, Hidetoshi Masuda, Yoichi Nii, Hidefumi Takahashi, Rodion Vladimirovich Belosludov, Shintaro Ishiwata, Mohammad Saeed Bahramy, Yoshinori Onose

  Proceedings of the National Academy of Sciences  ( 122(4) ) e2405839122 2025.01

  Research paper (scientific journal), Joint Work, Accepted

  • Access to Document (DOI)

• Band asymmetry–driven nonreciprocal electronic transport in a helimagnetic semimetal α-EuP ₃

  Alex Hiro Mayo, Darius-Alexandru Deaconu, Hidetoshi Masuda, Yoichi Nii, Hidefumi Takahashi, Rodion Vladimirovich Belosludov, Shintaro Ishiwata, Mohammad Saeed Bahramy, Yoshinori Onose

  Proceedings of the National Academy of Sciences (Proceedings of the National Academy of Sciences)  122 ( 4 )  2025.01

  ISSN  0027-8424

  　View Summary

  Chiral magnetic textures give rise to unconventional magnetotransport phenomena such as the topological Hall effect and nonreciprocal electronic transport. While the correspondence between topology or symmetry of chiral magnetic structures and such transport phenomena has been well established, a microscopic understanding based on the spin-dependent band structure in momentum space remains elusive. Here, we demonstrate how a chiral magnetic superstructure introduces an asymmetry in the electronic band structure and triggers a nonreciprocal electronic transport in a centrosymmetric helimagnet α-EuP ₃ . The magnetic structure of α-EuP ₃ is highly tunable by a magnetic field and closely coupled to its semimetallic electronic band structure, enabling a systematic study across chiral and achiral magnetic phases on the correspondence between nonreciprocal transport and electronic band asymmetry. Our findings reveal how a microscopic change in the magnetic configuration of charge carriers can lead to nonreciprocal electronic transport, paving the way for designing chiral magnets with desirable properties.

  • Access to Document (DOI)

• Observation of Nonreciprocal Diffraction of Surface Acoustic Wave

  Y. Nii, K. Yamamoto, M. Kanno, S. Maekawa, Y. Onose

  Physical Review Letters (American Physical Society (APS))  134 ( 2 )  2025.01

  Lead author, Corresponding author, Accepted,  ISSN  0031-9007

  　View Summary

  Rectification phenomenon caused by the simultaneous breaking of time reversal
  and spatial inversion symmetries has been extended to a wide range of
  (quasi)particles and waves; however, the nonreciprocal diffraction, which is
  the imbalance of upward and downward deflections, was previously observed only
  for photons and remained to be extended to other (quasi)particles. In this
  study, we present evidence of the nonreciprocal diffraction of surface acoustic
  wave (SAW) utilizing a magnetoelastic grating on a SAW device. Asymmetric
  diffraction intensities were observed when the ferromagnetic resonance was
  acoustically excited. Based on a theoretical model, we attribute the
  microscopic origin of this phenomenon to the resonant scattering involving
  ferromagnetic resonance excitations. The novel property may pave an avenue to
  further development of SAW devices for various purposes, including microwave
  communications and quantum engineering applications.
  

  • Access to Document (DOI)

• A high-temperature multiferroic Tb2(MoO4)3

  Shimon Tajima, Hidetoshi Masuda, Yoichi Nii, Shojiro Kimura, Yoshinori Onose

  Communications Materials (Springer Science and Business Media LLC)  5 ( 1 )  2024.12

  　View Summary

  Abstract
  
  Magnetoelectric mutual control in multiferroics, which is the electric control of magnetization, or reciprocally the magnetic control of polarization has attracted much attention because of its possible applications to spintronic devices, multi-bit memories, and so on. While the required working temperature for the practical application is much higher than room temperature, which ensures stable functionality at room temperature, the reported working temperatures were at most around room temperature. Here, we demonstrated magnetic control of ferroelectric polarization at 432 K in ferroelectric and ferroelastic Tb₂(MoO₄)₃, in which the polarity of ferroelectric polarization is coupled to the orthorhombic strain below the transition temperature 432 K. The paramagnetic but strongly magnetoelastic Tb³⁺ magnetic moments enable the magnetic control of ferroelectric and ferroelastic domains; the ferroelectric polarization is controlled depending on whether the magnetic field is applied along [110] or [1$$\bar{1}$$0]. This result may pave a new avenue for designing high-temperature multiferroics.

  • Access to Document (DOI)

display all >>

Reviews, Commentaries, etc. 【 Display / hide 】

Reviews, Commentaries, etc. 【 Display / hide 】

• Magnetoelastic study on the itinerant helimagnet SrFeO₃ and reconsideration of the phase diagram

  厳正輝, 今城周作, 鬼頭俊介, 徳永祐介, 新居陽一, 池田暁彦, 小濱芳允, 金道浩一, 石渡晋太郎, 有馬孝尚, 有馬孝尚

  日本物理学会講演概要集(CD-ROM) 79 ( 1 )  2024

  ISSN  2189-079X

• Observation of phonon dispersion at low temperature phases in FeV₂O₄ using synchrotron X-ray inelastic scattering

  萬條太駿, 鬼頭俊介, 片山尚幸, 中村真一, 勝藤拓郎, 新居陽一, 新居陽一, 有馬孝尚, 有馬孝尚, 長谷川巧, 石川大介, 石川大介, BARON A. Q. R., BARON A. Q. R., 澤博

  日本物理学会講演概要集(CD-ROM) 76 ( 2 )  2021

  ISSN  2189-079X

• Observation of 3d orbital state in spinel oxide FeV₂,O₄ with Fe and V having orbital degree of freedom

  萬條太駿, 鬼頭俊介, 片山尚幸, 野村悠祐, 有田亮太郎, 有田亮太郎, 新居陽一, 新居陽一, 有馬孝尚, 有馬孝尚, 澤博

  日本物理学会講演概要集(CD-ROM) 75 ( 2 )  2020

  ISSN  2189-079X

• Direct observation of valence electron density distribution in AV2O4(A = Fe,Mn) using core differential Fourier synthesis method

  萬條太駿, 鬼頭俊介, 片山尚幸, 新居陽一, 有馬孝尚, 有馬孝尚, 勝藤拓郎, 勝藤拓郎, 澤博

  日本物理学会講演概要集(CD-ROM) 75 ( 1 )  2020

  ISSN  2189-079X

• コア差フーリエ合成解析によるFeV₂O₄の軌道秩序の観測 II

  萬條太駿, 鬼頭俊介, 片山尚幸, 新居陽一, 有馬孝尚, 澤博

  日本物理学会講演概要集(CD-ROM) 74 ( 1 )  2019

  ISSN  2189-079X

display all >>

Research Projects of Competitive Funds, etc. 【 Display / hide 】

Research Projects of Competitive Funds, etc. 【 Display / hide 】

• 対称性の破れた絶縁体における新しい変位電流応答の開拓

  2024.06

  -

  2026.03

  挑戦的研究(萌芽), Research grant, Principal investigator

• 対称性の破れた絶縁体における新しい変位電流応答の開拓

  2024.06

  -

  2026.03

  挑戦的研究（萌芽）, Principal investigator

• Gigahertz Phononic Devices with Topological Functionalities

  2024.04

  -

  2027.03

  基盤研究(B), Principal investigator

• 超低損失なGHzトポロジカルフォノニックデバイスの創出

  2024.04

  -

  2027.03

  日本学術振興会 科学研究費助成事業 基盤研究(B), Principal investigator

• 先端計測による強相関フォノニクスと熱機能の開拓

  2023.04

  -

  2030.03

  創発的研究支援事業, Principal investigator

display all >>

Awards 【 Display / hide 】

Awards 【 Display / hide 】

• 文部科学大臣表彰 若手科学者賞

  2024.04

• 第140回金研講演会 優秀ポスター賞

  新居陽一, 廣金優二, 是常隆, 石川大介, Alfred Q. R. Baron, 小野瀬佳文, 2021.05, 東北大学金属材料研究所, キラル磁性体MnSi のフォノン分散に及ぼす対称性の破れの効果

• Best poster awards in Summit of Materials Science conference

  Yoichi Nii, 2018.10, Institute for Materials Research, Tohoku university

• JPSJ Editor's Choice, Microwave Magnetochiral Effect in the Non-centrosymmetric Magnet CuB2O4

  Yoichi Nii, Ryo Sasaki, Yusuke Iguchi, Yoshinori Onose, 2017.01, Journal of the Physical Society of Japan

Courses Taught 【 Display / hide 】

Courses Taught 【 Display / hide 】

• PRESENTATION TECHNIQUE

  2025

• LABORATORY IN SCIENCE

  2025

• INDEPENDENT STUDY ON FUNDAMENTAL SCIENCE AND TECHNOLOGY

  2025

• GRADUATE RESEARCH ON FUNDAMENTAL SCIENCE AND TECHNOLOGY 2

  2025

• GRADUATE RESEARCH ON FUNDAMENTAL SCIENCE AND TECHNOLOGY 1

  2025

display all >>

Memberships in Academic Societies 【 Display / hide 】

Memberships in Academic Societies 【 Display / hide 】

• 応用物理学会, 

  2022

  -

  Present

• 日本物理学会, 

  2009

  -

  Present