Tunnelling anisotropic magnetoresistance of Fe/GaAs/Ag(001) junctions from first principles: Effect of hybridized interface resonances

TL;DR

This study uses first-principles calculations to show how hybridized interface resonances in Fe/GaAs/Ag(001) tunnel junctions can significantly enhance tunnelling anisotropic magnetoresistance, with effects depending on barrier thickness.

Contribution

It reveals the role of hybridized interface resonances in enhancing TAMR and provides a detailed analysis of their impact through first-principles and tight-binding models.

Findings

TAMR shows a non-monotonic dependence on barrier thickness.

Hybridization at interfaces creates hot spots affecting tunnelling.

A simple tight-binding model reproduces key features of the first-principles results.

Abstract

Results of first-principles calculations of the Fe/GaAs/Ag(001) epitaxial tunnel junctions reveal that hybridization of interface resonances formed at both interfaces can enhance the tunnelling anisotropic magnetoresistance (TAMR) of the systems. This mechanism is manifested by a non-monotonic dependence of the TAMR effect on the thickness of the tunnel barrier, with a maximum for intermediate thicknesses. A detailed scan of k-resolved transmissions over the two-dimensional Brillouin zone proves an interplay between a few hybridization-induced hot spots and a contribution to the tunnelling from the vicinity of the Gamma-bar point. This interpretation is supported by calculated properties of a simple tight-binding model of the junction which reproduce qualitatively most of the features of the first-principles theory.