  Spin-orbit torque (SOT) provides an efficient way to achieve charge-to-spin
conversion and can switch perpendicular magnetization, which is essential for
designing novel energy-efficient spintronic devices. An out-of-plane SOT could
directly switch perpendicular magnetization. Encouragingly, field-free
perpendicular magnetization switching of a two-dimensional (2D) material
WTe2/ferromagnet (FM) bilayer has been reported recently, but the working
temperature (200 K) is below room temperature. Here, we report the field-free
perpendicular magnetization switching carried out at room temperature on a
WTe2/Pt/Co/Pt multilayer film. Controlled experiments confirm that the
field-free switching is caused by the in-plane antidamping SOT generated in the
Pt/Co/Pt multilayer and the out-of-plane generated in the a-axis WTe2 thin
film. This work offers a potential method for using spintronic devices made of
two-dimensional materials at room temperature.
