  We report a comprehensive study on the intrinsic spin Hall conductivity (SHC)
of semimetals MoTe2 and WTe2 by ab initio calculation. Large SHC and desirable
spin Hall angles have been discovered, due to the strong spin orbit coupling
effect and low charge conductivity in semimetals. Diverse anisotropic SHC
values, attributed to the unusual reduced-symmetry crystalline structure, have
been revealed. We report an effective method on SHC optimization by electron
doping, and exhibit the mechanism of SHC variation respect to the energy
shifting by the spin Berry curvature. Our work provides insights into the
realization of strong spin Hall effects in 2D systems.
