Nonequilibrium spin transport in graphene proximitized by WSe₂

Ming-Hao Liu^1*

¹Department of Physics, National Cheng Kung University, Tainan, Taiwan

* Presenter:Ming-Hao Liu, email:minghao.liu@phys.ncku.edu.tw

Spin-orbit coupling (SOC) in graphene is known to be negligibly weak, on the order of 0.1 meV, due to its composed atom, carbon, a light element of atomic number only 6. A decade ago, it was found that the SOC in graphene can be significantly enhanced simply by attaching it to a transition metal dichalcogenide of strong SOC, known as the spin-orbit proximity effect [1]. Our recent theoretical work in collaboration with a transport experiment on graphene proximitized by WSe₂ reported a supporting number for the SOC as strong as 12.6 meV [2]. Inspired by this finding, here I present numerical results on nonequilibrium spin Hall accumulation in graphene/WSe₂ heterostructures based on the Landauer-Keldysh formalism [3]. Combined with the recently discussed "radial" Rashba SOC [4], nonequilibrium spin precession will be shown, paving an alternative way to the realization of the Datta-Das spin transistor [5].
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[1] A. Avsar, J. Y. Tan, T. Taychatanapat, J. Balakrishnan, G. Koon, Y. Yeo, J. Lahiri, A. Carvalho, A. S. Rodin, E. O’Farrell, et al., Nat. Commun. 5, 4875 (2014).
[2] Q. Rao, W.-H. Kang, H. Xue, Z. Ye, X. Feng, K. Watanabe, T. Taniguchi, N. Wang, M.-H. Liu, and D.-K. Ki, Nat. Commun. 14, 6124 (2023).
[3] B. K. Nikolic, S. Souma, L. P. Zarbo, and J. Sinova, Phys. Rev. Lett. 95, 046601 (2005).
[4] W.-H. Kang, M. Barth, A. Costa, A. Garcia-Ruiz, A. Mrenca-Kolasinska, M.-H. Liu, and D. Kochan, Phys. Rev. Lett., accepted (2024).
[5] Datta and B. Das, Appl. Phys. Lett. 56, 665 (1990).

Keywords: graphene, spin-orbit coupling, spin Hall effect, tight-binding model, Landauer-Keldysh formalism