Anisotropy of spin relaxation and transverse transport in metals

TL;DR

This paper investigates how spin relaxation and transverse transport properties in metals vary with orientation due to spin-orbit interaction, revealing significant anisotropy affecting spintronic applications.

Contribution

It provides first-principles analysis of anisotropic spin relaxation and transverse transport in metals, highlighting the impact of spin-orbit coupling on electronic state properties.

Findings

Anisotropy significantly affects spin-mixing parameter and Berry curvature.

Pronounced directional dependence observed in spin relaxation and Hall effects.

Implications for designing spintronic devices with orientation-dependent properties.

Abstract

Using first principles methods we explore the anisotropy of the spin relaxation and transverse transport properties in bulk metals with respect to the direction of the spin quantization axis in paramagnets or of the spontaneous magnetization in ferromagnets. Owing to the presence of the spin-orbit interaction the orbital and spin character of the Bloch states depends sensitively on the orientation of the spins relative to the crystal axes. This leads to drastic changes in quantities which rely on interband mixing induced by the spin-orbit interaction. The anisotropy is particularly striking for quantities which exhibit spiky and irregular distribution in the Brillouin zone, such as the spin-mixing parameter or the Berry curvature of the electronic states. We demonstrate this for three cases: (i) the Elliott-Yafet spin-relaxation mechanism in paramagnets with structural inversion symmetry; (ii) the intrinsic anomalous Hall effect in ferromagnets; and (iii) the spin Hall effect in paramagnets. We discuss the consequences of the pronounced anisotropic behavior displayed by these properties for spin-polarized transport applications.