Large magnetoresistance in an electric field controlled antiferromagnetic tunnel junction

TL;DR

This paper proposes an electric-field controlled antiferromagnetic tunnel junction that exhibits large magnetoresistance, enabling low-power spintronic devices by leveraging magnetic phase transitions in Mn3Pt.

Contribution

It introduces a novel AFM tunnel junction design that uses electric fields to control magnetic states via phase transitions, with detailed first-principles analysis.

Findings

Achieves over 100% magnetoresistance through magnetic phase transition.

Band structure analysis explains the origin of large TMR.

Demonstrates robustness with amorphous barriers.

Abstract

Large magnetoresistance effect controlled by electric field rather than magnetic field or electric current is a preferable routine for designing low power consumption magnetoresistance-based spintronic devices. Here we propose an electric-field controlled antiferromagnetic (AFM) tunnel junction with structure of piezoelectric substrate/Mn3Pt/SrTiO3/Pt operating by the magnetic phase transition (MPT) of antiferromagnet Mn3Pt through its magneto-volume effect. The transport properties of the proposed AFM tunnel junction have been investigated by employing first-principles calculations. Our results show that a magnetoresistance over hundreds of percent is achievable when Mn3Pt undergoes MPT from a collinear AFM state to a non-collinear AFM state. Band structure analysis based on density functional calculations shows that the large TMR can be attributed to the joint effect of significant different Fermi surface of Mn3Pt at two AFM phases and the band symmetry filtering effect of the SrTiO3 tunnel barrier. In addition, other than single-crystalline tunnel barrier, we also discuss the robustness of the proposed magnetoresistance effect by considering amorphous AlOx barrier. Our results may open perspective way for effectively electrical writing and reading of the AFM state and its application in energy efficient magnetic memory devices.