Revealing Controllable Anisotropic Magnetoresistance in Spin Orbit Coupled Antiferromagnet Sr2IrO4

TL;DR

This paper demonstrates controllable anisotropic magnetoresistance in Sr2IrO4 thin films driven by spin-orbit coupling and magnetic field, revealing new mechanisms for antiferromagnetic spintronics with potential for magnetic memory applications.

Contribution

It introduces a novel method to control anisotropic magnetoresistance in antiferromagnetic Sr2IrO4 via spin-orbit coupling and magnetic field, highlighting the role of Jeff=1/2 states.

Findings

Magnetic field induces contour rotation of fourfold anisotropic magnetoresistance.

Emergence of a minimal magnetoresistance point under certain conditions.

First principles calculations link band-gap changes to Ir isospin rotation.

Abstract

Antiferromagnetic spintronics actively introduces new principles of magnetic memory, in which the most fundamental spin-dependent phenomena, i.e. anisotropic magnetoresistance effects, are governed by an antiferromagnet instead of a ferromagnet. A general scenario of the antiferromagnetic anisotropic magnetoresistance effects mainly stems from the magnetocrystalline anisotropy related to spin-orbit coupling. Here we demonstrate magnetic field driven contour rotation of the fourfold anisotropic magnetoresistance in bare antiferromagnetic Sr2IrO4/SrTiO3 (001) thin films hosting a strong spin-orbit coupling induced Jeff=1/2 Mott state. Concurrently, an intriguing minimal in the magnetoresistance emerges. Through first principles calculations, the band-gap engineering due to rotation of the Ir isospins is revealed to be responsible for these emergent phenomena, different from the traditional scenario where relatively more conductive state was obtained usually when magnetic field was applied along the magnetic easy axis. Our findings demonstrate a new efficient route, i.e. via the novel Jeff=1/2 state, to realize controllable anisotropic magnetoresistance in antiferromagnetic materials.