Strong Correlation Quantum Structure Research Team

Principal Investigator

PI Name Takahisa Arima
Degree Ph.D.
Title Team Leader
Brief Resume
1988TORAY Co. Ltd.
1991Research Associate, Faculty of Science, University of Tokyo
1994Ph.D. (Science), University of Tokyo
1995Research Associate, Graduate School of Engineering, University of Tokyo
1995Associate Professor, Institute of Materials Science, University of Tsukuba
2004Professor, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University
2011Professor, Graduate School of Frontier Sciences, University of Tokyo (-present)
2007Team Leader, Spin Order Research Team, RIKEN SPring-8 Center (-2014)
2013Team Leader, Strong Correlation Quantum Structure Research Team, RIKEN Center for Emergent Matter Science (-present)


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 Sciences, Physics


X-ray scattering
Neutron scattering
Electron diffraction
Structure science


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.


Takahisa Arima

Team Leader takahisa.arima[at] R

Taro Nakajima

Research Scientist

Kiyou Shibata

Special Postdoctoral Researcher

Victor Ukleev

Postdoctoral Researcher

Kazuhisa Kakurai

Senior Visiting Scientist


  • Jun 10, 2017 RIKEN RESEARCH A skyrmion square dance
    Applying a magnetic field can switch a grid of magnetic vortices between triangular and square arrangements
  • Jul 03, 2015 RIKEN RESEARCH 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 RIKEN RESEARCH Flicking the switch on spin-driven devices
    Compressing magnetically and electrically active crystals in one direction unlocks exotic spintronic switching activity


2-1 Hirosawa, Wako, Saitama 351-0198 Japan