Gauge theory applied to magnetic lattices

Abstract

Micromagnetic exchange is usually derived by performing the continuum limit of the Heisenberg model on a cubic lattice, where the exchange integrals are assumed to be identical for all nearest neighbors. This limitation normally imposes the use of a microscopic theory to explain the appearance of higher order magnetic interactions such as the Dzyaloshinskii-Moriya interaction (DMI). In this paper we combine graph- and gauge field- theory to simultaneously account for the symmetries of the crystal, the effect of spin-orbit coupling and their interplay on a micromagnetic level. We obtain a micromagnetic theory accounting for the crystal symmetry constraints at all orders in exchange and show how to successfully predict the form of micromagnetic DMI in all 32 point groups.