Tunnelling anisotropic magnetoresistance due to antiferromagnetic CoO tunnel barriers.

K Wang,T Bolhuis,M P De Jong,J G M Sanderink,W G Van Der Wiel

doi:10.1038/srep15498

Abstract

A new approach in spintronics is based on spin-polarized charge transport phenomena governed by antiferromagnetic (AFM) materials. Recent studies have demonstrated the feasibility of this approach for AFM metals and semiconductors. We report tunneling anisotropic magnetoresistance (TAMR) due to the rotation of antiferromagnetic moments of an insulating CoO layer, incorporated into a tunnel junction consisting of sapphire(substrate)/fcc-Co/CoO/AlOx/Al. The ferromagnetic Co layer is exchange coupled to the AFM CoO layer and drives rotation of the AFM moments in an external magnetic field. The results may help pave the way towards the development of spintronic devices based on AFM insulators.

Highlights

Heterostructures comprising AFM Sr2IrO4 layers and FM La2/3Sr1/3MnO3 electrodes[12]
We report tunnelling anisotropic magnetoresistance (TAMR) effects of up to 2.5% in tunnel junctions that contain insulating AFM CoO tunnel barriers, which are exchange coupled to FM Co electrodes
Domain state model calculations have been reported, suggesting that the relative orientation of the magnetic field and the AFM magnetic easy axis may play an important role in the magnetization reversal process[17]

Summary

Introduction

Heterostructures comprising AFM Sr2IrO4 layers and FM La2/3Sr1/3MnO3 electrodes[12]. We report TAMR effects of up to 2.5% in tunnel junctions that contain insulating AFM CoO tunnel barriers, which are exchange coupled to FM Co electrodes (see Fig. 1). We will show that the TAMR effect is governed by the rotation of the AFM moments at the Co/CoO interface rather than the FM moments of the Co electrode. Ever since the discovery of the exchange bias effect in Co/CoO core-shell nanoparticles by Meiklejohn and Bean in 195613,14, the impact of the Co/CoO interfacial spin system on magnetization reversal processes has been intensively studied, in particular using anisotropic magnetoresistance (AMR) measurements of bi-layer Co/CoO structures[15,16]. Our results show that these interfacial spin systems hold great promise for the active manipulation of spin polarized transport

Methods

Results

Conclusion