Finite-temperature micromagnetic model bridging atomic- and macro-scale magnetism

Abstract

A multi-scale finite-temperature micromagnetic model is presented, based on the Landau-Lifshitz equation and the Bernoulli differential equation. This model accurately reproduces classic Maxwell magnetostatics of paramagnets for high temperatures and accurately reproduces standard micromagnetics described by the conventional Landau-Lifshitz model in ferromagnets. The Landau-Lifshitz-Bernoulli (LLBe) model can, by design, directly couple atomic-scale simulations with micromagnetics and output consistent predictions of bulk magnetic properties at finite temperatures, from below to above the material's Curie temperature. The LLBe model is validated against established solvers: MUMAX3 for zero-temperature micromagnetics, and FEMCE for high-temperature classic magnetostatics. We present an application of the LLBe model by simulating Heat-Assisted magnetic recording on a thin magnetic track with local heating, demonstrating the multi-scale finite-temperature capabilities of the LLBe.