Spatial Separation of Carrier Spin by the Valley Hall Effect in Monolayer WSe2 Transistors

Elyse Barré; Jean Anne C Incorvia; Suk Hyun Kim; Connor J McClellan; Eric Pop; H-S Philip Wong; Tony F Heinz

doi:10.1021/acs.nanolett.8b03838

Spatial Separation of Carrier Spin by the Valley Hall Effect in Monolayer WSe₂ Transistors

Nano Lett. 2019 Feb 13;19(2):770-774. doi: 10.1021/acs.nanolett.8b03838. Epub 2019 Jan 2.

Authors

Elyse Barré¹, Jean Anne C Incorvia^{1

2}, Suk Hyun Kim³, Connor J McClellan¹, Eric Pop^{1

4}, H-S Philip Wong¹, Tony F Heinz^{3

5}

Affiliations

¹ Department of Electrical Engineering , Stanford University , Stanford , California 94305 , United States.
² Department of Electrical and Computer Engineering , University of Texas at Austin , Austin , Texas 78712 , United States.
³ Departments of Applied Physics and Photon Science , Stanford University , Stanford , California 94305 , United States.
⁴ Department of Materials Science and Engineering , Stanford University , Stanford , California 94305 , United States.
⁵ SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States.

PMID: 30601667
DOI: 10.1021/acs.nanolett.8b03838

Abstract

We investigate the valley Hall effect (VHE) in monolayer WSe₂ field-effect transistors using optical Kerr rotation measurements at 20 K. While studies of the VHE have so far focused on n -doped MoS₂, we observe the VHE in WSe₂ in both the n - and p -doping regimes. Hole doping enables access to the large spin-splitting of the valence band of this material. The Kerr rotation measurements probe the spatial distribution of the valley carrier imbalance induced by the VHE. Under current flow, we observe distinct spin-valley polarization along the edges of the transistor channel. From analysis of the magnitude of the Kerr rotation, we infer a spin-valley density of 44 spins/μm, integrated over the edge region in the p -doped regime. Assuming a spin diffusion length less than 0.1 μm, this corresponds to a spin-valley polarization of the holes exceeding 1%.

Keywords: Tungsten diselenide; magneto-optical Kerr effect; spintronics; valleytronics.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.