This thesis summarizes my studies of the spin Hall effect (SHE) in PtHf alloy. The SHE is an emerging route for spintronics which enables conversion of charge currents into spin currents without ferromagnets or external magnetic fields. The spin current generated by the SHE has been utilized to manipulate magnetization of adjacent nanomagnets. Therefore, a large conversion ratio between the spin and charge currents, i.e., a large spin Hall angle, is highly desirable in practical applications. By analyzing the data from the adiabatic (low frequency) harmonic Hall voltage measurement, the damping-like spin torque efficiency, which is the lower bound of the spin Hall angle, can be estimated. I demonstrated that the damping-like spin torque efficiency can be increased by over 50% by doping Hf impurity of 1% in Pt.