Heavy metal-based two-dimensional van der Waals materials
have
a large, coupled spin and valley Hall effect (SVHE) that has potential
use in spintronics and valleytronics. Optical measurements of the
SVHE have largely been performed below 30 K, and understanding of
the SVHE-induced spin/valley polarizations that can be electrically
generated is limited. Here, we study the SVHE in monolayer p-type
tungsten diselenide (WSe2). Kerr rotation (KR) measurements
show the spatial distribution of the SVHE at different temperatures,
its persistence up to 160 K, and that it can be electrically modulated
via gate and drain bias. A spin/valley drift and diffusion model together
with a reflection measurement and a four-port electrical measurement
is used to interpret the KR data. A lower-bound spin/valley lifetime
is predicted to be of 40 ns and a mean free path of 240 nm below 90
K, 2 orders of magnitude higher than a previous work that uses similar
methods. The spin/valley polarization on the edge is calculated to
be ∼4% at 45 K. These results are important steps toward practical
use of the SVHE.
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