Significant Role of Interfacial Spin-Orbit Coupling in the Spin-to-Charge Conversion in Pt/NiFe Heterostructure

For the spin-to-charge conversion (SCC) in heavy metal/ferromagnet (HM/FM) heterostructure, the contribution of interfacial spin-orbit coupling (SOC) remains controversial. Here, we investigate the SCC process of the Pt/NiFe heterostructure by the spin pumping in YIG/Pt/NiFe/IrMn multilayers. Due to the exchange bias of NiFe/IrMn structure, the NiFe magnetization can be switched between magnetically unsaturated and saturated states by opposite resonance fields of YIG layer. The spin-pumping signal is found to decrease significantly when the NiFe magnetization is changed from the saturated state to the unsaturated state. Theoretical analysis indicates that the interfacial spin absorption is enhanced for the above-mentioned NiFe magnetic state change, which results in the increased and decreased spin flow in the Pt layer and across the Pt/NiFe interface, respectively. These results demonstrate that in our case the interfacial SOC effect at the Pt/NiFe interface is dominant over the bulk inverse spin Hall effect in the Pt layer. Our work reveals a significant role of interfacial SOC in the SCC in HM/FM heterostructure, which can promote the development of high-efficiency spintronic devices through interfacial engineering.

Automated summary

In this study, the significant role of interfacial spin-orbit coupling (SOC) in spin-to-charge conversion (SCC) process in Pt/NiFe heterostructure was investigated. The spin-pumping experiment showed that the spin-pumping signal decreased when the magnetization of NiFe switched from the saturated state to the unsaturated state. Theoretical analysis revealed that the interfacial spin absorption was enhanced during this magnetization change, resulting in the changes of spin flow in the Pt layer and across the Pt/NiFe interface. These findings highlight the importance of interfacial SOC in SCC process in HM/FM heterostructures.