Prospect for room temperature tunneling anisotropic magnetoresistance effect: density of states anisotropies in CoPt systems

TL;DR

This paper predicts significant room-temperature tunneling anisotropic magnetoresistance effects in ferromagnetic metals like CoPt, based on ab initio calculations, suggesting new simpler spintronic device designs.

Contribution

It introduces the first ab initio prediction of sizable TAMR effects in room-temperature metallic ferromagnets, expanding potential spintronic applications.

Findings

Predicted large TAMR effects in CoPt systems at room temperature.

Validated density of states anisotropy predictions with experimental magnetocrystalline anisotropy data.

Identified specific ferromagnetic structures with enhanced spin-orbit coupling for TAMR applications.

Abstract

Tunneling anisotropic magnetoresistance (TAMR) effect, discovered recently in (Ga,Mn)As ferromagnetic semiconductors, arises from spin-orbit coupling and reflects the dependence of the tunneling density of states in a ferromagnetic layer on orientation of the magnetic moment. Based on ab initio relativistic calculations of the anisotropy in the density of states we predict sizable TAMR effects in room-temperature metallic ferromagnets. This opens prospect for new spintronic devices with a simpler geometry as these do not require antiferromagnetically coupled contacts on either side of the tunnel junction. We focus on several model systems ranging from simple hcp-Co to more complex ferromagnetic structures with enhanced spin-orbit coupling, namely bulk and thin film L1$_0$-CoPt ordered alloys and a monatomic-Co chain at a Pt surface step edge. Reliability of the predicted density of states anisotropies is confirmed by comparing quantitatively our ab initio results for the magnetocrystalline anisotropies in these systems with experimental data.