Microscopic Theory of Rashba Interaction in Magnetic Metal

TL;DR

This paper develops a microscopic theory of Rashba spin-orbit coupling in magnetic metals, linking structural inversion symmetry breaking, orbital angular momentum, and band-specific Rashba parameters, supported by first-principles calculations.

Contribution

It introduces a microscopic Hamiltonian-based model explaining Rashba interaction in magnetic metals, emphasizing band-specific effects and orbital mixing contributions.

Findings

Rashba parameter varies and can reverse sign across bands.

Orbital mixing with heavy elements enhances Rashba interaction.

First-principles calculations support the theoretical model.

Abstract

Theory of Rashba spin-orbit coupling in magnetic metals is worked out from microscopic Hamiltonian describing d-orbitals. When structural inversion symmetry is broken, electron hopping between $d$-orbitals generates chiral ordering of orbital angular momentum, which combines with atomic spin-orbit coupling to result in the Rashba interaction. Rashba parameter characterizing the interaction is band-specific, even reversing its sign from band to band. Large enhancement of the Rashba parameter found in recent experiments is attributed to the orbital mixing of 3d magnetic atoms with non-magnetic heavy elements as we demonstrate by first-principles and tight-binding calculations.