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)


Our unit aims to develop new magnetic materials with topological functions and high-performance magnetic functions based on materials synthesis. We will develop topological magnetic materials and ferromagnetic/antiferromagnetic materials in intermetallic and oxide compounds 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


Strongly correlated electron systems


Development of new room-temperature antiskyrmion materials

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 focused on room-temperature ferromagnets (Fe,Ni)3P with S4 symmetry. Our systematic material syntheses and magnetic measurements have revealed that the magnetic anisotropy is dramatically changed by doping with 4d transition metals. In particular, Pd-doping changes the magnetic anisotropy from easy-plane to easy-axis and leads to the formation of stable antiskyrmions above room temperature.


(a) Schematic spin texture of an antiskyrmion. (b) Schematic crystal structure of M3P (M: transition metals) with S4 symmetry. (c) Temperature dependence of magnetic anisotropy energy for various compositions of (Fe,Ni)3P doped with 4d transition metals.


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


  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, V. Ukleev, C. D. Dewhurst, R. Cubitt, A. Kikkawa, Y. Tokunaga, H. M. Ronnow, Y. Tokura, and Y. Taguchi

    Metastable skyrmion lattices governed by magnetic disorder and anisotropy in beta-Mn-type chiral magnets

    Phys. Rev. B 102, 064408 (2020)
  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)


Hirosawa 2-1, Wako 351-0198 Japan