Modulation of spin-torque ferromagnetic resonance with a nanometer-thick platinum by ionic gating

Ryo Ohshima,Teruya Shinjo,Yuichiro Ando,Yuto Kohsaka,Masashi Shiraishi

doi:10.1038/s41598-021-01310-6

Abstract

The spin Hall effect (SHE) and inverse spin Hall effect (ISHE) have played central roles in modern condensed matter physics especially in spintronics and spin-orbitronics, and much effort has been paid to fundamental and application-oriented research towards the discovery of novel spin–orbit physics and the creation of novel spintronic devices. However, studies on gate-tunability of such spintronics devices have been limited, because most of them are made of metallic materials, where the high bulk carrier densities hinder the tuning of physical properties by gating. Here, we show an experimental demonstration of the gate-tunable spin–orbit torque in Pt/Ni80Fe20 (Py) devices by controlling the SHE using nanometer-thick Pt with low carrier densities and ionic gating. The Gilbert damping parameter of Py and the spin-memory loss at the Pt/Py interface were modulated by ionic gating to Pt, which are compelling results for the successful tuning of spin–orbit interaction in Pt.

Highlights

The spin Hall effect (SHE) and inverse spin Hall effect (ISHE) have played central roles in modern condensed matter physics especially in spintronics and spin-orbitronics, and much effort has been paid to fundamental and application-oriented research towards the discovery of novel spin–orbit physics and the creation of novel spintronic devices
The ISHE almost vanished in Pt grown on yttrium-iron-garnet (YIG) under a gate voltage of + 2 V using ionic gel as a gate material, where spin current was injected from the YIG under its ferromagnetic resonance (FMR)
We experimentally demonstrated the gate-tunable SHE of 1.2 nm-thick Pt grown on 3 nm-thick Py as manifestation of the gate-tunable spin–orbit interaction (SOI) by employing spintorque FMR (ST-FMR) and ionic gating techniques

Summary

Introduction

The spin Hall effect (SHE) and inverse spin Hall effect (ISHE) have played central roles in modern condensed matter physics especially in spintronics and spin-orbitronics, and much effort has been paid to fundamental and application-oriented research towards the discovery of novel spin–orbit physics and the creation of novel spintronic devices. Ionic gating has opened a wide variety of novel physics, such as superconductivity in insulating o xide[13] and transition metal dichalcogenides (TMD)[14,15], chiral light emission from monolayer T MD16, and tunable Curie temperature (magnetization) in ultrathin Co17. These great achievements were attributed to the potential of ionic gating to accumulate very dense charges by the formation of an extraordinarily thin electric double. A positive gate voltage application enabling electron accumulation gives rise to an upshift of the Fermi level from the intrinsic one in Pt, which allows suppression of the spin Hall conductivity, i.e., suppression of the ISHE

Methods

Findings

Discussion

Conclusion