Unified Framework for Micromagnetic Modeling of Ferro-, Ferri-, and Antiferromagnetic Materials at Mesoscopic Scale: Domain Wall Dynamics as a Case Study

We introduce a formulation of a two-sublattice micromagnetic model, which can describe the statics and dynamics of ferromagnets, antiferromagnets, and ferrimagnets. Such a formulation is based on the normalization of exchange, Dzyaloshinskii-Moriya interaction, and anisotropy parameters with respect to the square modulus of the saturation magnetization for each sublattice. We show a study of the statics and dynamics of domain walls (DWs) focusing on antiferromagnets and ferrimagnets because of their potential ultrafast performance in terms of dynamics and robustness against external magnetic perturbations. Our results show a direction to design DW-based nanodevices in ferrimagnets with a superlinear velocity increasing as a function of the spin-orbit torque amplitude by working near, but still below, the threshold current for the excitation of self-oscillations.