Imaging of pure spin-valley diffusion current in WS2-WSe2 heterostructures

Chenhao Jin; Jonghwan Kim; M Iqbal Bakti Utama; Emma C Regan; Hans Kleemann; Hui Cai; Yuxia Shen; Matthew James Shinner; Arjun Sengupta; Kenji Watanabe; Takashi Taniguchi; Sefaattin Tongay; Alex Zettl; Feng Wang

doi:10.1126/science.aao3503

Imaging of pure spin-valley diffusion current in WS₂-WSe₂ heterostructures

Science. 2018 May 25;360(6391):893-896. doi: 10.1126/science.aao3503. Epub 2018 May 24.

Authors

Chenhao Jin¹, Jonghwan Kim^{1

2}, M Iqbal Bakti Utama^{1

3}, Emma C Regan^{1

4}, Hans Kleemann¹, Hui Cai⁵, Yuxia Shen⁵, Matthew James Shinner¹, Arjun Sengupta¹, Kenji Watanabe⁶, Takashi Taniguchi⁶, Sefaattin Tongay⁵, Alex Zettl^{1

7

8}, Feng Wang^{9

7

8}

Affiliations

¹ Department of Physics, University of California at Berkeley, Berkeley, CA 94720, USA.
² Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 790-784, Korea.
³ Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, CA 94720, USA.
⁴ Graduate Group in Applied Science and Technology, University of California at Berkeley, Berkeley, CA 94720, USA.
⁵ School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ 85287, USA.
⁶ National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan.
⁷ Division of Material Science, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
⁸ Kavli Energy NanoSciences Institute at the University of California at Berkeley and Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
⁹ Department of Physics, University of California at Berkeley, Berkeley, CA 94720, USA. [email protected].

PMID: 29798880
DOI: 10.1126/science.aao3503

Abstract

Transition metal dichalcogenide (TMDC) materials are promising for spintronic and valleytronic applications because valley-polarized excitations can be generated and manipulated with circularly polarized photons and the valley and spin degrees of freedom are locked by strong spin-orbital interactions. In this study we demonstrate efficient generation of a pure and locked spin-valley diffusion current in tungsten disulfide (WS₂)-tungsten diselenide (WSe₂) heterostructures without any driving electric field. We imaged the propagation of valley current in real time and space by pump-probe spectroscopy. The valley current in the heterostructures can live for more than 20 microseconds and propagate over 20 micrometers; both the lifetime and the diffusion length can be controlled through electrostatic gating. The high-efficiency and electric-field-free generation of a locked spin-valley current in TMDC heterostructures holds promise for applications in spin and valley devices.

Publication types

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