Strong Correlation Quantum Structure Research Group

Principal Investigator
Outline
Members
Publications
Articles

Principal Investigator

PI Name

Takahisa Arima

Degree

Ph.D.

Title

Group Director

Brief Resume

1988	TORAY Co. Ltd.
1991	Research Associate, Faculty of Science, University of Tokyo
1994	Ph.D. (Science), University of Tokyo
1995	Research Associate, Graduate School of Engineering, University of Tokyo
1995	Associate Professor, Institute of Materials Science, University of Tsukuba
2001	Group Leader, ERATO Tokura Spin Super Structure Project (-2006)
2004	Professor, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University
2011	Professor, Graduate School of Frontier Sciences, University of Tokyo (-present)
2007	Team Leader, Spin Order Research Team, RIKEN SPring-8 Center (-2014)
2013	Team Leader, Strong Correlation Quantum Structure Research Team, RIKEN Center for Emergent Matter Science
2023	Deputy Director, RIKEN Center for Emergent Matter Science (CEMS)
2023	Group Director, Strong Correlation Quantum Structure Research Group, RIKEN Center for Emergent Matter Science (-present)
2024	Director, RIKEN Center for Emergent Matter Science (CEMS) (-present)

Outline

Strongly correlated electron systems may exhibit various interesting emergent phenomena such as superconductivity, colossal magneto-resistance, and giant magneto-electric effects. These emergent phenomena are directly associated with the spatial distributions as well as the spatial and temporal fluctuations of atoms, electron density, and spin density. To reveal these phenomena, we perform crystallographic and magnetic structure analyses, spectroscopies, and microscopies by using synchrotron x-rays, neutrons, and high-energy electron beams.

Research Fields

Materials Science, Physics

Keywords

X-ray scattering
Neutron scattering
Electron diffraction
Structure science
Imaging

Results

Spin-driven Ferroelectricity and Electromagnon in Multiferroic Y-type Hexaferrite Compounds

Y-type hexaferrite compounds are composed of an alternate stacking of spinel block layers and hexagonal perovskite block layers. The magnetic anisotropy of each layer and effective exchange interaction are dependent on the composition. As a consequence, various magnetic orders appears in the temperature-magnetic field plane. It is predicted that two kinds of magnetic orders, transverse cone and double fan, can host electric polarization via the inverse Dzyalloshinsky-Moriya interaction. We performed measurements of magnetization, electric polarization, and spin-polarized neutron scattering in BaSrCo₂Fe₁₁AlO₂₂. It has been found that the alternate longitudinal cone first appears by cooling from a high temperature at zero magnetic field. If a magnetic field is once applied perpendicular to the c-axis at low temperatures, the double fan replaces and survives even after the magnetic field is turned off. The electric polarization is also induced along the axis perpendicular both to the c-axis and to the magnetic field. The electric polarization is reversed by switching the magnetic field direction. Inelastic spin-polarized neutron scattering has predicted that both the double fan and alternative longitudinal cone may host an electromagnon (magnon excited by THz electric field).

Magnetic-field induced reversal of electric polarization and possible change in magnetic structure in a Y-type hexaferrite BaSrCo₂Fe₁₁AlO₂₂.

Members

Takahisa Arima	Group Director	takahisa.arima[at]riken.jp
Masaki Gen	Special Postdoctoral Researcher
Kamini Gautam	Postdoctoral Researcher

Publications

V. Ukleev, O. Utesov, L. Yu, C. Luo, K. Chen, F. Radu, Y. Yamasaki, N. Kanazawa, Y. Tokura, T. Arima, J. S. White

Signature of anisotropic exchange interaction revealed by vector-field control of the helical order in a FeGe thin plate

Phys. Rev. Research 3, 013094 (2021)
Y. Ishii, K. Yamamoto, Y. Yokoyama, M. Mizumaki, H. Nakao, T. Arima, Y. Yamasaki

Soft-X-ray Vortex Beam Detected by Inline Holography

Phys. Rev. Appl. 14, 064069 (2020)
T. Nakajima, T. Oda, M. Hino, H. Endo, K. Ohishi, K. Kakurai, A. Kikkawa, Y. Taguchi, Y. Tokura, T. Arima

Crystallization of magnetic skyrmions in MnSi investigated by neutron spin echo spectroscopy

Phys. Rev. Research 2, 043393 (2020)
V. Ukleev, Y. Yamasaki, O. Utesov, K. Shibata, N. Kanazawa, N. Jaouen, H. Nakao, Y. Tokura, and T.-h. Arima

Metastable solitonic states in the strained itinerant helimagnet FeGe

Phys. Rev. B 102, 014416 (2020)
S. Gao, M. Hirschberger, O. Zaharko, T. Nakajima, T. Kurumaji, A. Kikkawa, J. Shiogai, A. Tsukazaki, S. Kimura, S. Awaji, Y. Taguchi, T.-h. Arima, and Y. Tokura

Ordering phenomena of spin trimers accompanied by a large geometrical Hall effect

Phys. Rev. B 100, 241115 (2019)

Articles

Apr 20, 2018 Electrical pulses shift the boundaries between magnetic patterns

Electricity can be used to control magnetic patterns in an alloy, opening up the possibility of using them in high-performance devices
Feb 23, 2018 Chiral magnets show bulk diode effect due to spin fluctuation

Materials with left- and right-handed responses to current exhibit an intriguing diode effect
Jun 10, 2017 A skyrmion square dance

Applying a magnetic field can switch a grid of magnetic vortices between triangular and square arrangements
Jul 03, 2015 A surprisingly simple magnetic flip

A simple technique makes it possible to control the spin directions of ‘magnetic twins’ hiding inside metallic crystals
May 18, 2015 Flicking the switch on spin-driven devices

Compressing magnetically and electrically active crystals in one direction unlocks exotic spintronic switching activity