The Origin of Tunneling Anisotropic Magnetoresistance in Break Junctions

TL;DR

This paper uses first-principles calculations to explain the origin of tunneling anisotropic magnetoresistance (TAMR) in Ni and Co break junctions, attributing it to resonant states affected by spin-orbit coupling and magnetization orientation.

Contribution

It reveals that TAMR arises from resonant states localized in electrodes near the break, influenced by spin-orbit coupling, providing a microscopic understanding of the phenomenon.

Findings

TAMR strongly depends on magnetization direction due to resonant states.

Resonant states' energy and broadening are affected by spin-orbit coupling.

Results align with recent experimental observations.

Abstract

First-principles calculations of electron tunneling transport in Ni and Co break junctions reveal strong dependence of the conductance on the magnetization direction, an effect known as tunneling anisotropic magnetoresistance (TAMR). The origin of this phenomenon stems from resonant states localized in the electrodes near the junction break. The energy and broadening of these states is strongly affected by the magnetization orientation due to spin-orbit coupling, causing TAMR to be sensitive to bias voltage on a scale of a few mV. Our results bear a resemblance to recent experimental data and suggest that TAMR driven by resonant states is a general phenomenon typical for magnetic broken contacts and other experimental geometries where a magnetic tip is used to probe electron transport.