Exciton spin Hall effect in arc-shaped strained WSe2

Generating a pure spin current using electrons, which have degrees of freedom beyond spin, such as electric charge and valley index, presents challenges. In response, we propose a mechanism based on intervalley exciton dynamics in strained transition metal dichalcogenides (TMDs) to achieve the in an electrically insulating regime, without the need for an external electric field. The interplay between strain gradients and strain-induced pseudomagnetic fields results in a net Lorentz force on long-lived intervalley excitons in <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msub><a:mi>WSe</a:mi><a:mn>2</a:mn></a:msub></a:math>, carrying nonzero spin angular momentum. This process generates an exciton-mediated pure spin Hall current, resulting in opposite-sign spin accumulations and local magnetization on the two sides of the single-layer arc-shaped TMD. We demonstrate that the magnetic field induced by spin accumulation, at approximately <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mrow><b:mo>∼</b:mo><b:mi>mT</b:mi></b:mrow></b:math>, can be detected using techniques such as superconducting quantum interference magnetometry or spatially resolved magneto-optical Faraday and Kerr rotations. Published by the American Physical Society 2024