Spin-orbit torque and spin pumping in YIG/Pt with interfacial insertion layers

TL;DR

This study explores how ultrathin insertion layers at the YIG/Pt interface affect spin-orbit torque, spin pumping, and damping, revealing the importance of interfacial magnetization in spin current transmission.

Contribution

It provides experimental insights into how different insertion layers modulate spin transport phenomena at YIG/Pt interfaces, highlighting the role of interfacial magnetic properties.

Findings

Cu suppresses spin-orbit torque and spin pumping

NiFe (Py) enhances spin-orbit torque and spin pumping

Py insertion increases Gilbert damping beyond spin pumping effects

Abstract

We experimentally investigate spin-orbit torque and spin pumping in Y$_3$Fe$_5$O$_{12}$(YIG)/Pt bilayers with ultrathin insertion layers at the interface. An insertion layer of Cu suppresses both spin-orbit torque and spin pumping, whereas an insertion layer of Ni$_{80}$Fe$_{20}$ (permalloy, Py) enhances them, in a quantitatively consistent manner with the reciprocity of the two spin transmission processes. However, we observe a large enhancement of Gilbert damping with the insertion of Py that cannot be accounted for solely by spin pumping, suggesting significant spin-memory loss due to the interfacial magnetic layer. Our findings indicate that the magnetization at the YIG-metal interface strongly influences the transmission and depolarization of pure spin current.