Momentum-Dependent Spin Splitting by Collinear Antiferromagnetic Ordering

TL;DR

This paper investigates how collinear antiferromagnetic order can induce momentum-dependent spin splitting in electronic bands without relying on atomic spin-orbit coupling, revealing new mechanisms in light-element materials.

Contribution

It clarifies the symmetry and microscopic conditions for spin splitting in collinear antiferromagnets and links ordering patterns to spin splitting across 32 crystallographic groups.

Findings

Spin splitting can occur without atomic spin-orbit coupling in certain antiferromagnets.

The study maps the relationship between magnetic orderings and spin splitting for multiple crystal groups.

Potential applications include spin-current generation and magneto-striction effects in light-element materials.

Abstract

We clarify the macroscopic symmetry and microscopic model-parameter conditions for emergence of spin-split electronic band structure in collinear antiferromagnets without atomic spin-orbit coupling. By using the microscopic multipole descriptions, we elucidate the fundamental degree of freedom in a cluster unit of an antiferromagnet giving rise to an effective spin-orbit interaction through the anisotropic kinetic motions of electrons. We show a correspondence of the ordering patterns and resultant momentum-dependent spin splitting for 32 crystallographic point groups after demonstrating two intuitive examples of four-sublattice pyrochlore and tetragonal systems. Our study unveils potential features of collinear antiferromagnets with considerably weak spin-orbit coupling in light-element materials and 3$d$ transition metal oxides, which can be utilized for a spin-current generation by electric (thermal) current and a magneto-striction effect.