Tunnel magnetoresistance and robust room temperature exchange bias with multiferroic BiFeO3 epitaxial thin films

TL;DR

This paper demonstrates the use of multiferroic BiFeO3 thin films in spintronic devices, achieving significant tunnel magnetoresistance and stable room temperature exchange bias, advancing the development of robust spintronic components.

Contribution

It introduces novel applications of BiFeO3 epitaxial films in spintronics, including tunnel barriers and exchange bias effects at room temperature, with enhanced stability and performance.

Findings

Positive tunnel magnetoresistance up to 30% at low temperature

Room temperature exchange bias of ~60 Oe with robustness upon cycling

No training effects observed in exchange bias

Abstract

We report on the functionalization of multiferroic BiFeO3 epitaxial films for spintronics. A first example is provided by the use of ultrathin layers of BiFeO3 as tunnel barriers in magnetic tunnel junctions with La2/3Sr1/3MnO3 and Co electrodes. In such structures, a positive tunnel magnetoresistance up to 30% is obtained at low temperature. A second example is the exploitation of the antiferromagnetic spin structure of a BiFeO3 film to induce a sizeable (~60 Oe) exchange bias on a ferromagnetic film of CoFeB, at room temperature. Remarkably, the exchange bias effect is robust upon magnetic field cycling, with no indications of training.