Thickness dependence study of current-driven ferromagnetic resonance in Y3Fe5O12/heavy metal bilayers

TL;DR

This study investigates how the thickness of YIG in YIG/heavy metal bilayers affects current-driven ferromagnetic resonance, revealing that the Oersted field primarily drives magnetization dynamics over spin-transfer torque.

Contribution

It provides a detailed analysis of the thickness dependence of current-induced torques in YIG/heavy metal bilayers, highlighting the dominance of the Oersted field.

Findings

Oersted field dominates over spin-transfer torque

YIG thickness influences the FMR response

Spin rectification and spin pumping are characterized

Abstract

We use ferromagnetic resonance to study the current-induced torques in YIG/heavy metal bilayers. YIG samples with thickness varying from 14.8 nm to 80 nm, with Pt or Ta thin film on top, are measured by applying a microwave current into the heavy metals and measuring the longitudinal DC voltage generated by both spin rectification and spin pumping. From a symmetry analysis of the FMR lineshape and its dependence on YIG thickness, we deduce that the Oersted field dominates over spin-transfer torque in driving magnetization dynamics.