Spin-torque ferromagnetic resonance in electrochemically etched metallic device

Abstract

We demonstrate the quantification of spin–orbit torque efficiencies using spin-torque ferromagnetic resonance (ST-FMR) combined with electrochemical etching of a Fe/Pt bilayer. The electrochemical etching of the ST-FMR device using an ionic liquid enables to study spin–orbit effective fields, as well as an Oersted field, by varying the ferromagnetic-layer thickness. This allows to disentangle the field-like (FL) effective field and Oersted field, enabling to determine the damping-like and FL torque efficiencies in the single device. This robust technique opens a possibility to explore the spin–orbit torques in exotic materials and systems.