| 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 and high-performance magnetic functionalities. We focus on the exploration of novel intermetallic compounds and alloys using single-crystal growth and non-equilibrium methods, and elucidate their magnetic structures and topological properties through various experimental techniques, including magnetometry, electrical transport measurements, scanning probe microscopy, and neutron scattering.
Physics, Materials Sciences, Engineering
Strongly correlated electron systems
Magnetism
Topological materials
Magnetic materials with a kagome lattice have attracted considerable attention in recent years because their geometric structure gives rise to a variety of topological properties. However, materials that exhibit topological phenomena above room temperature have been limited so far. We have successfully synthesized single crystals of MnRhP, a magnetic material with a distorted kagome lattice, and systematically investigated its magnetic structure and electrical transport properties. We found that this material hosts magnetic skyrmions above room temperature and exhibits a large anomalous Hall effect. Furthermore, first-principles calculations reveal that this anomalous Hall effect originates from the Berry curvature associated with topological nodal lines. This study demonstrates that MnRhP is a rare kagome lattice magnet that possesses topological properties in both real space and momentum space.
(a) Schematic crystal structure of MnRhP. (b) Schematic spin texture of a magnetic skyrmion. (c) Temperature dependence of the anomalous Hall conductivity (AHC) in MnRhP.
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
| Kosuke Karube | Unit Leader | kosuke.karube[at]riken.jp | |
|---|---|---|---|
Nikola Subotic |
Postdoctoral Researcher |
Room-Temperature Magnetic Skyrmions and Intrinsic Anomalous Hall Effect in a Nodal-Line Kagomé Ferromagnet MnRhP
Giant Hall effect in a highly conductive frustrated magnet GdCu2
Anisotropy-Dependent Decay of Room Temperature Metastable Skyrmions and a Nascent Double-q Spin Texture in Co8Zn9Mn3
Doping Control of Magnetic Anisotropy for Stable Antiskyrmion Formation in Schreibersite (FeNi)3P with S4 symmetry
Room-temperature antiskyrmions and sawtooth surface textures in a non-centrosymmetric magnet with S4 symmetry
Disordered skyrmion phase stabilized by magnetic frustration in a chiral magnet
Robust metastable skyrmions and their triangular-square lattice structural transition in a high-temperature chiral magnet
Hirosawa 2-1, Wako 351-0198 Japan
E-mail：
kosuke.karube[at]riken.jp