Demagnetization in micromagnetics: magnetostatic self-interactions of bulk chiral magnetic skyrmions

Abstract

We develop a theoretical and numerical framework for three-dimensional bulk chiral magnets that includes the full magnetostatic dipole-dipole interaction and its back-reaction on the magnetization. Assuming translational invariance along one spatial direction, we analyze the effect of dipolar interactions on three Dzyaloshinskii--Moriya interaction (DMI) terms -- Dresselhaus, Rashba, and Heusler -- corresponding to Bloch, N\'eel, and antiskyrmion textures. In the absence of the dipolar interaction, these three DMI terms are gauge-equivalent and yield degenerate skyrmion energies. Incorporating the non-local dipole-dipole interaction breaks this degeneracy: Bloch skyrmions remain unaffected, N\'eel skyrmions shrink slightly, and Heusler antiskyrmions lose axial symmetry and stabilize into square-lattice crystals. The system is solved using a non-local numerical relaxation method that self-consistently computes the magnetostatic potential from Poisson's equation. Our results show that long-range dipolar interactions can stabilize bulk antiskyrmion crystals in translationally invariant three-dimensional chiral magnets.