Tunneling anisotropic magnetoresistance of NiFe/IrMn/MgO/Pt stack: An antiferromagnet based spin-valve

TL;DR

This paper demonstrates a novel spin-valve device using an antiferromagnet, showing large TAMR effects and enabling magnetic characterization through electronic transport.

Contribution

It introduces a NiFe/IrMn/MgO/Pt stack with an AFM-based spin-valve exhibiting over 100% TAMR, a new approach for AFM spintronics.

Findings

>100% TAMR signal observed

AFM moments manipulated by low magnetic fields

Transport characteristics governed by AFM moments

Abstract

Spin-valve is a microelectronic device in which high and low resistance states are realized by utilizing both charge and spin of carriers. Spin-valve structures used in modern hard drive read-heads and magnetic random access memories comprise two ferromagnetic (FM) electrodes whose relative magnetization orientations can be switched between parallel and antiparallel configurations, yielding the desired giant or tunneling magnetoresistance effect. In this paper we demonstrate >100$% spin-valve-like signal in a NiFe/IrMn/MgO/Pt stack with an antiferromagnet (AFM) on one side and a non-magnetic metal on the other side of the tunnel barrier. FM moments in NiFe are reversed by external fields <50mT and the exchange-spring effect of NiFe on IrMn induces rotation of AFM moments in IrMn which is detected by the measured tunneling anisotropic magnetoresistance (TAMR). Our work demonstrates a spintronic element whose transport characteristics are governed by an AFM. It demonstrates that sensitivity to low magnetic fields can be combined with large, spin-orbit coupling induced magneto-transport anisotropy using a single magnetic electrode. The AFM-TAMR provides means to study magnetic characteristics of AFM films by an electronic transport measurement.