Temperature and thickness dependence of tunneling anisotropic magnetoresistance in exchange-biased Py/IrMn/MgO/Ta stacks

TL;DR

This study explores how the thickness ratio and temperature affect tunneling anisotropic magnetoresistance in NiFe/IrMn bilayers, revealing specific electric responses and confirming TAMR's stability up to room temperature.

Contribution

It provides new insights into the thickness and temperature dependence of TAMR in exchange-biased stacks, identifying specific conditions for distinct electric responses.

Findings

TAMR persists up to room temperature despite thermal noise

Four distinct electric response scenarios based on thickness ratio

Characteristic voltage dependence confirms TAMR stability

Abstract

We investigate the thickness and temperature dependence of a series of Ni0:8Fe0:2/Ir0:2Mn0:8 bilayer samples with varying thickness ratio of the ferromagnet/antiferromagnet (tFM/tAFM) in order to explore the exchange coupling strengths in tunneling anisotropic magnetoresistance (TAMR) devices. Specific values of tFM/tAFM lead to four distinct scenarios with specific electric responses to moderate magnetic fields. The characteristic dependence of the measured TAMR signal on applied voltage allows us to confirm its persistence up to room temperature despite an overlapped contribution by a thermal magnetic noise.