Tunneling Magnetoresistance in Noncollinear Antiferromagnetic Tunnel Junctions

TL;DR

This paper demonstrates a significant tunneling magnetoresistance effect in non-collinear antiferromagnetic tunnel junctions, enabling electric detection of the Neel vector for advanced AFM spintronic applications.

Contribution

It introduces a method to detect the Neel vector in non-collinear AFM metals using TMR effects predicted by first-principles calculations.

Findings

TMR effect up to 300% predicted in Mn3Sn-based junctions

Four non-volatile resistance states depending on Neel vector orientation

Potential applicability to other non-collinear AFM metals like Mn3Ge and Mn3Ga

Abstract

Antiferromagnetic (AFM) spintronics has emerged as a subfield of spintronics driven by the advantages of antiferromagnets producing no stray fields and exhibiting ultrafast magnetization dynamics. The efficient method to detect an AFM order parameter, known as the N\'eel vector, by electric means is critical to realize concepts of AFM spintronics. Here, we demonstrate that non-collinear AFM metals, such as Mn3Sn, exhibit a momentum dependent spin polarization which can be exploited in AFM tunnel junctions to detect the N\'eel vector. Using first-principles calculations based on density functional theory, we predict a tunneling magnetoresistance (TMR) effect as high as 300% in AFM tunnel junctions with Mn3Sn electrodes, where the junction resistance depends on the relative orientation of their N\'eel vectors and exhibits four non-volatile resistance states. We argue that the spin-split band structure and the related TMR effect can also be realized in other non-collinear AFM metals like Mn3Ge, Mn3Ga, Mn3Pt, and Mn3GaN. Our work provides a robust method for detecting the N\'eel vector in non-collinear antiferromagnets via the TMR effect, which may be useful for their application in AFM spintronic devices.