Spin-orbit-torque driven magnetoimpedance in Pt-layer/magnetic-ribbon heterostructures

TL;DR

This study explores how spin-orbit torque from platinum layers influences magnetoimpedance in magnetic ribbons, revealing current and layer thickness effects, and demonstrating a novel method for detecting spin Hall effect in low-frequency regimes.

Contribution

It introduces the use of magnetoimpedance measurements to probe spin-orbit torque effects in high permeability magnetic ribbons, a novel approach in the low-frequency regime.

Findings

MI frequency shift increases with current amplitude and Pt thickness

SOT affects magnetic permeability detectable via impedance spectroscopy

FMR shows increased damping due to SHE in Pt layers

Abstract

When a flow of electron passes through a paramagnetic layer with strong spin-orbit-coupling such as platinum (Pt), a net spin current is produced via spin Hall effect (SHE). This spin current can exert a torque on the magnetization of an adjacent ferromagnetic layer which can be probed via magnetization dynamic response, e.g. spin-torque ferromagnetic resonance (ST-FMR). Nevertheless, that effect in lower frequency magnetization dynamic regime (MHz) where skin effect occurs in high permeability ferromagnetic conductors namely the magneto-impedance (MI) effect can be fundamentally important which has not been studied so far. Here, by utilizing the MI effect in magnetic-ribbon/Pt heterostructure with high magnetic permeability that allows the ac current effectively confined at the skin depth of ~100 nm thickness, the effect of spin-orbit-torque (SOT) induced by the SHE probed via MI measurement is investigated. We observed a systematic MI frequency shift that increases by increasing the applied current amplitude and thickness of the Pt layer (varying from 0 nm to 20 nm). In addition, the role of Pt layer in ribbon/Pt heterostructure is evaluated with ferromagnetic resonance (FMR) effect representing standard Gilbert damping increase as the result of presence of the SHE. Our results unveil the role of SOT in dynamic control of the transverse magnetic permeability probed with impedance spectroscopy as useful and valuable technique for detection of future SHE devices.