Current-induced magnetization switching in a nano-scale CoFeB-MgO magnetic tunnel junction under in-plane magnetic field

N Ohshima,J Llandro,S Fukami,H Ohno,F Matsukura,H Sato,S Kanai

doi:10.1063/1.4977224

Abstract

We study current-induced magnetization switching properties of a magnetic tunnel junction with junction diameter of 19 nm and resistance-area product of 6 Ωμm2 in the nanosecond regime with and without in-plane magnetic field. At zero field, for both parallel (P)-to-anti-parallel (AP) and AP-to-P switchings, the probability of switching PSW approaches unity with the increase of pulse voltage duration τP. However, under in-plane magnetic field, PSW for P-to-AP switching starts to saturate at a value lower than unity with increasing τP, while AP-to-P switching remains the same as in the absence of in-plane magnetic field. This in-plane field dependence of PSW can be partially explained by the influence of electric-field modulation of magnetic anisotropy.

Highlights

Magnetization switching in spintronics devices by electrical means is one of the most important phenomena for application
We investigate the current-induced STT switching of a CoFeB-MgO magnetic tunnel junctions (MTJs) with perpendicular easy axis with diameter of 19 nm, and report that in addition to STT, the electric-field effect appears to play a role in determining switching characteristics, which manifests itself under the presence of in-plane magnetic field
A pulse generator and dc measurement setup are connected to the MTJ through rf and dc port of a bias-tee, respectively

Summary

Introduction

Magnetization switching in spintronics devices by electrical means is one of the most important phenomena for application. For magnetic tunnel junctions (MTJs), two switching schemes have been studied; one is the spin-transfer-torque-induced switching (STT-switching),[1,2] and the other is the electric-field-induced switching.[3,4,5,6] For the electric-field-induced switching, the magnetization reversal takes place through magnetization precession induced by magnetic anisotropy modulation.[3,4,5,6] In this work, we investigate the current-induced STT switching of a CoFeB-MgO MTJ with perpendicular easy axis with diameter of 19 nm, and report that in addition to STT, the electric-field effect appears to play a role in determining switching characteristics, which manifests itself under the presence of in-plane magnetic field

Methods

Results

Conclusion