Spin pumping and large field-like torque at room temperature in sputtered amorphous WTe2−x films

Yihong Fan,Protyush Sahu,Junyang Chen,Jacob Held,Jian-Ping Wang,Mahendra Dc,Delin Zhang,Hongshi Li,Andre Mkhoyan,Thomas Peterson

doi:10.1063/1.5124688

Abstract

We studied the spin-to-charge and charge-to-spin conversion at room temperature in sputtered WTe2−x (x = 0.8) (t)/Co20Fe60B20(6 nm) heterostructures. Spin pumping measurements were used to characterize the spin-to-charge efficiency, and the spin efficiency was calculated to be larger than ∼0.035. Second harmonic Hall measurements were carried out to estimate the charge-to-spin conversion ratio. We found that the system exhibits a large field-like torque (spin torque efficiency ∼0.1) and small damping-like torque (spin torque efficiency ∼0.001) compared to those reported for heavy metals. High-resolution transmission electron microscopy images show that the WTe2−x layer is amorphous, which may enhance the spin swapping effect by inducing large interfacial spin–orbit scattering, thus contributing to a large field-like torque.

Highlights

O scitation.org/journal/apm characterize the spin-to-charge conversion, and the resulting efficiency is larger than 0.045, as defined by the ratio of charge current and spin current.16 second harmonic Hall measurements were carried out to characterize the charge-to-spin conversion of WTe2−x films, which is defined as the ratio between spin conductivity and charge conductivity
We found that the system exhibits a large field-like torque and small damping-like torque compared to those reported for heavy metals
We report our investigation on magnetronsputtered WTe2−x thin films that exhibit a large room temperature (RT) field-like torque (FLT)

Summary

Introduction

O scitation.org/journal/apm characterize the spin-to-charge conversion, and the resulting efficiency is larger than 0.045, as defined by the ratio of charge current and spin current.16 second harmonic Hall measurements were carried out to characterize the charge-to-spin conversion of WTe2−x films, which is defined as the ratio between spin conductivity (the spin torque strength) and charge conductivity. High-resolution transmission electron microscopy images show that the WTe2−x layer is amorphous, which may enhance the spin swapping effect by inducing large interfacial spin–orbit scattering, contributing to a large field-like torque.

Results

Conclusion