Emergent Functional Magnetic Materials Research Unit

Principal Investigator

PI Name
Kosuke Karube
Title
Unit Leader
HP
https://researchmap.jp/karube/
Brief Resume
2015 Ph.D., Kyoto University
2015 Postdoctoral Researcher, Strong-Correlation Materials Research Group, RIKEN Center for Emergent Matter Science (CEMS) 
2019 Research Scientist, Strong-Correlation Materials Research Group, RIKEN CEMS
2023 Senior Research Scientist, Strong-Correlation Materials Research Group, RIKEN CEMS
2023 Unit Leader, Emergent Functional Magnetic Materials Research Unit, Cross-Divisional Materials Research Program, RIKEN CEMS (-present)

Outline

Our unit aims to develop new magnetic materials with topological functions and high-performance magnetic functions based on materials synthesis. We will develop novel intermetallic compounds and alloys using singe crystal growth and rapid quenching methods, and elucidate their magnetic structures and topological properties through various measurement techniques such as magnetometry, scanning probe microscopy, and neutron scattering.

Research Fields

Physics, Materials Sciences, Engineering

Keywords

Strongly correlated electron systems
Magnetism
Topological materials

Results

Development of new room-temperature antiskyrmion materials and observation of magnetic domain structures

Skyrmions are vortex-like topological spin textures and anticipated to be used for spintronics devices. Antiskyrmions are anti-vortex topological spin textures with topological numbers of opposite sign to those of skyrmions. While antiskyrmions have been expected to form in magnets with D2d or S4 symmetry, they have only been observed in Heusler alloys with D2d symmetry. We discovered a new material (Fe,Ni,Pd)3P as a host of antiskyrmions above room temperature. Furthermore, we revealed anisotropic fractal magnetic domain structures in bulk crystals using magnetic force microscopy and small-angle neutron scattering.

(a) Schematic spin texture of an antiskyrmion. (b) Single crystal of (Fe,Ni,Pd)3P. (c) Magnetic force microscopy image of fractal magnetic domain texture. (d) Magnetic small-angle neutron scattering pattern.
Reproduced from [Karube et al. (2022). J. Appl. Cryst. 55, 1392-1400] with permission of the International Union of Crystallography

Members

Kosuke Karube Unit Leader kosuke.karube[at]riken.jp

Nikola Subotic

 Postdoctoral Researcher

Publications

  1. K. Karube, V. Ukleev, F. Kagawa, Y. Tokura, Y. Taguchi, and J. S. White

    Unveiling the anisotronic fractal magnetic domain structure in bulk crystals of antiskyrmion host (FeNiPd)3P by small-angle neutron scattering

    J. Appl. Crystallogr. 55, 1392-1400 (2022)
  2. K. Karube, L. Peng, J. Masell, M. Hemmida, H.-A. K. von Nidda, I. Kezsmarki, X. Yu, Y. Tokura, and Y. Taguchi

    Doping Control of Magnetic Anisotropy for Stable Antiskyrmion Formation in Schreibersite (FeNi)3P with S4 symmetry

    Adv. Mater. 34, 2108770 (2022)
  3. K. Karube, L. C. Peng, J. Masell, X. Z. Yu, F. Kagawa, Y. Tokura, and Y. Taguchi

    Room-temperature antiskyrmions and sawtooth surface textures in a non-centrosymmetric magnet with S4 symmetry

    Nat. Mater. 20, 335 (2021)
  4. K. Karube, J. S. White, D. Morikawa, C. D. Dewhurst, R. Cubitt, A. Kikkawa, X. Yu, Y. Tokunaga, T.-h. Arima, H. M. Ronnow, Y. Tokura, and Y. Taguchi

    Disordered skyrmion phase stabilized by magnetic frustration in a chiral magnet

    Sci. Adv. 4, aar7043 (2018)
  5. K. Karube, J. S. White, N. Reynolds, J. L. Gavilano, H. Oike, A. Kikkawa, F. Kagawa, Y. Tokunaga, H. M. Ronnow, Y. Tokura, and Y. Taguchi

    Robust metastable skyrmions and their triangular-square lattice structural transition in a high-temperature chiral magnet

    Nat. Mater. 15, 1237 (2016)

Contact Us

Hirosawa 2-1, Wako 351-0198 Japan

E-mail：
kosuke.karube[at]riken.jp