Compositional dependence of spintronic properties in Pt/GdCo films

GdCo films have been widely used in spintronic applications, owing largely to their tunable degree of ferrimagnetic compensation. However, all key properties likewise depend on the alloy composition, and a systematic study of the interdependent spintronic properties with composition has not been reported. Here, we report the compositional dependence of key spintronic properties, including anisotropy, symmetric, and antisymmetric (Dzyaloshinskii-Moriya, DMI) exchange interactions, effective spin Hall angle, and domain wall mobility in a 3 nm Pt/GdCo composition series. We measure the magnetic anisotropy and determine an interfacial Pt/Co and bulk GdCo pair-ordering contribution to total anisotropy. Additionally, we estimate the exchange stiffness of all three interactions in GdCo as a function of composition. We conduct two types of domain wall motion experiments on patterned racetracks to determine the effective spin Hall angle and current-driven domain wall mobility. We find a 5x increase in effective spin Hall angle with increasing Gd concentration, suggesting an improvement in spin transfer efficiency in rare earth materials. Finally, we observe a monotonic decrease in the DMI strength with increasing Gd content, suggesting that DMI arises from the Pt/Co interfacial interaction.