Enhanced spin current generation near magnetic transition in amorphous cobalt silicon

Large spin-orbit torque has been observed in fully amorphous iron silicide [1]. While the concentration dependence of spin-orbit torque in iron silicide can potentially arise from the change in density of states near the Fermi level, the role of magnetism in magnetic element silicide has not been fully understood. Here, we report large spin-orbit torque in fully amorphous cobalt silicide through in-plane harmonic Hall measurement. By varying the concentration between cobalt and silicon, we observed that the peak of spin-orbit torque efficiency coincides with the transition of the magnetic phase from non-ferromagnetic to ferromagnetic characterized through x-ray magnetic circular dichroism. Our observation of an enhanced spin current near the magnetic transition of amorphous cobalt silicon potentially demonstrates a new way of engineering and understanding spin current generation in magnetic element silicide systems.