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

  • Author(s): Jin, Chenhao;
  • Kim, Jonghwan;
  • Utama, M Iqbal Bakti;
  • Regan, Emma C;
  • Kleemann, Hans;
  • Cai, Hui;
  • Shen, Yuxia;
  • Shinner, Matthew James;
  • Sengupta, Arjun;
  • Watanabe, Kenji;
  • Taniguchi, Takashi;
  • Tongay, Sefaattin;
  • Zettl, Alex;
  • Wang, Feng
  • et al.
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.

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