SU($N$) altermagnetism: Lattice models, magnon modes, and flavor-split bands

TL;DR

This paper extends the concept of altermagnetism to SU(N) magnets, providing models and analyzing magnon and electronic band structures, revealing flavor-split bands and their properties.

Contribution

It introduces a general framework for SU(N) altermagnets, constructs corresponding Heisenberg models, and analyzes their magnon and electronic spectra.

Findings

Magnon bands exhibit altermagnetic splitting based on quantum numbers.

Flavor-split electronic bands show polarization effects.

Theoretical models connect symmetry principles to observable band structures.

Abstract

Altermagnetism, a type of magnetic order that combines properties of ferro- and antiferromagnets, has stirred great interest lately not only as a promising source of spintronics applications, but also as a potential gateway to exotic phases of matter. Here, we demonstrate how to generalize collinear altermagnetism to SU($N$) magnets with $N>2$. Guided by symmetry principles, we present a recipe to construct Heisenberg models for such generalized altermagnets and apply it explicitly for $N=3,4$. Using flavor-wave theory, we compute the excitation spectrum of a two-dimensional SU(3) model and show that it exhibits magnon bands with altermagnetic splitting according to magnetic quantum numbers; we connect this quantum-number splitting to the frequently used concept of magnon chirality. We also compute the electronic band structure for a metallic system of the same symmetry and map out the polarization of the resulting flavor-split bands.