  Magnetic heterostructure Mo/CoFeB/MgO has strong perpendicular magnetic
anisotropy and thermal stability. Through current-induced hysteresis loop shift
measurements, we show that the dampinglike spin-orbit torque (SOT) efficiency
of Mo/CoFeB/MgO heterostructure is $\xi_{DL}\approx -0.003\pm 0.001$ and fairly
independent of the annealing temperature from 300$^\circ$C to 400$^\circ$C.
Though $|\xi_{DL}|$ is small while compare to those from Ta or W-based
heterostructures, reversible current-induced SOT switching of a
thermally-stable Mo/CoFeB/MgO heterostruture can still be achieved.
Furthermore, we observe field-free current-induced switching from a
Mo/CoFeB/MgO structure with the Mo layer being wedge-deposited. Our results
indicate that even for a weak spin-orbit interaction 4d transition metal such
as Mo, it is still possible to generate sufficient spin current for
conventional SOT switching and to realize field-free current-induced switching
by structural engineering.
