Institute for Materials Research, Tohoku University, Japan

Abstract: 

The uprising spin-orbitronics exploits the interplay between the electron’s spin, the spin-orbit coupling and the breaking of structural/time reversal symmetry. Notably, the generation of a transverse pure spin current via the spin Hall effect in a material with large spin-orbit coupling offers new opportunities compared to the conventional spintronic devices, where the spin current source is limited to the intrinsic spin polarization of the ferromagnetic electrodes. To be even more competitive for realistic applications, the scalability, energy efficiency, and operation speed of spin-orbitronic devices need to be further improved. In the talk, I will go through my research efforts that have contributed to the realization of better spin-orbitronic devices. Firstly, I will introduce a scalable scheme based on the interlayer exchange coupling for realizing spin-orbit torque switching of a perpendicular ferromagnetic layer without an external field [1]. Next, I will demonstrate the spin-orbit torque switching of a thin Mn-Ga ferrimagnet with high perpendicular magnetic anisotropy [2] and the discovery of giant spin-orbit torque in single-layer Mn2RuxGa films [3]. These ferrimagnets can potentially offer faster switching speed than the ferromagnets. Finally, I will elucidate the mechanism of efficient charge-to-spin conversion in topological quantum materials. I will show how thermal fluctuation can be beneficial for enhancing the spin Hall effect in narrow-gap semimetallic Bi-Sb alloys [4]. The correlation between the anomalous Hall effect and the spin Hall effect in kagome-lattice magnetic Weyl semimetal Co3Sn2S2 will also be discussed.

Reference:

1. Y.-C. Lau et al., Nature Nanotechnology 11, 758–762 (2016).
2. Y.-C. Lau et al., Physical Review B 99, 064410 (2019).
3. S. Lenne†, Y.-C. Lau† et al., arXiv 1903.04432.
4. Z. Chi, Y.-C. Lau* et al., Science Advances 6, eaay2324 (2020).

Brief CV of Dr. Yong-Chang Lau: 

Dr. Yong-Chang Lau received his Master’s degree and French title of Engineer in Applied Physics and Engineering from “Institut National des Sciences Appliquées” (INSA) Toulouse, France. He then pursued his PhD studies in Trinity College Dublin, Ireland under the supervision of Prof. J.M.D. Coey and Prof. Plamen Stamenov. After obtaining his PhD degree in 2016, he moved to Japan, working as a JSPS international fellow and postdoc with Prof. Masamitsu Hayashi in University of Tokyo and National Institute for Materials Science (NIMS). In June 2019, he joined Institute for Materials Research, Tohoku University as a specially-appointed assistant professor. His research specializes in the development of new materials for spintronic applications and the experimental quantification of the spin-charge conversion efficiency. Currently, he is interested in exploring novel spin-charge interconversion phenomena in thin film heterostructures with strong spin-orbit coupling and their potential applications in memory, logic, or sensor.

Host: Prof. Wenhong Wang, State Key Laboratory of Magnetism

Contact: Shujuan Cui (崔书娟）

Email: sjcui@iphy.ac.cn

Tel: 82649894

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