Interface-controlled antiferromagnetic tunnel junctions

TL;DR

This paper proposes a novel antiferromagnetic tunnel junction design using bulk-spin-degenerate electrodes with A-type AFM stacking, enabling spin-polarized tunneling and large TMR effects, advancing AFM spintronics.

Contribution

It introduces a new AFMTJ prototype with magnetically uncompensated interfaces, demonstrated through first-principles calculations, expanding the potential for AFM-based spintronic devices.

Findings

Large negative TMR from interfacial magnetic moments

Fe4GeTe2 as a representative A-type AFM electrode

Switchable Ne9el vector in AFMTJs

Abstract

Magnetic tunnel junctions (MTJs) are the key building blocks of high-performance spintronic devices. While conventional MTJs rely on ferromagnetic (FM) materials, employing antiferromagnetic (AFM) compounds can significantly increase operation speed and packing density. Current prototypes of AFM tunnel junctions (AFMTJs) exploit antiferromagnets either as spin-filter insulating barriers or as metal electrodes supporting bulk spin-dependent currents. Here, we highlight a largely overlooked AFMTJ prototype, where bulk-spin-degenerate electrodes with an A-type AFM stacking form magnetically uncompensated interfaces, enabling spin-polarized tunneling currents and a sizable tunneling magnetoresistance (TMR) effect. Using first-principles quantum-transport calculations and the van der Waals (vdW) metal Fe$_{4}$GeTe$_{2}$ as a representative A-type AFM electrode, we demonstrate a large negative TMR arising solely from the alignment of interfacial magnetic moments. This prototype of AFMTJs can also be realized with various non-vdW A-type AFM metals that support roughness-insensitive surface magnetization. Beyond TMR, AFMTJs based on A-type antiferromagnets allow convenient switching of the N\'eel vector, opening a new paradigm for AFM spintronics that leverages spin-dependent properties at AFM interfaces.