From thermally induced magnonic spin current to current-induced spin-orbit torque

Ssu-Yen Huang^1*

¹Physics, National Taiwan University, Taipei, Taiwan

* Presenter:Ssu-Yen Huang, email:syhuang@phys.ntu.edu.tw

The generation, manipulation, and detection of spin current are major challenges in the field of spintronics and spin caloritronics. In this talk, we demonstrate the thermal spin current can be driven by light in magnetic materials, including magnonic spin current of the light-driven spin Seebeck effect (SSE) in magnetic insulator and spin-polarized current of the light-driven anomalous Nernst effect (ANE) in ferromagnetic metal [1]. By reversing the direction of the incident light, we are able to qualitatively distinguish the contributions to the transverse spin accumulation between the interfacial and bulk temperature gradients. We show that thermally induced magnonic spin current is a powerful tool for studying spin Hall materials. Next, we investigate current-induced spin-orbit torque (SOT) switching by utilizing spin Hall materials, In the case of heterostructure with perpendicular magnetic anisotropy (PMA), we demonstrate polarity-controlled field-free SOT switching in 3d Cr [2]. However, we do not observe conclusive evidence of SOT switching in antiferromagnet [3]. It still remains a challenge to unequivocally detect the antiferromagnetic Néel vector, before and after the SOT switching.

Reference:
[1] Y. J. Chen and S. Y. Huang, Phys. Rev. B 99, 094426 (2019).
[2] T. C. Chuang, C. F. Pai, and S. Y. Huang, Phys. Rev. Applied 11, 061005 (2019) (Letter).
[3] C. C. Chiang, S. Y. Huang, D. Qu, P. H. Wu, C. L. Chien, Phys. Rev. Lett., in press (2019)

Keywords: magnonic spin current , spin-orbit torque , magnetic insulator , antiferromagnet