BDF2-type integrator for Landau-Lifshitz-Gilbert equation in micromagnetics: a-priori error estimates
This provides rigorous error estimates for a computationally efficient scheme in micromagnetics, addressing a known bottleneck in numerical analysis of LLG.
The paper proves optimal-order convergence rates for a BDF2-type integrator for the Landau-Lifshitz-Gilbert equation, achieving first-order in space and second-order in time, establishing the first higher-order-in-time linear integrator that converges to both weak and strong solutions.
We consider the Landau-Lifshitz-Gilbert equation (LLG), which models time-dependent micromagnetic phenomena. We analyze a fully discrete scheme that combines first-order finite elements in space with a BDF2 method in time. The method requires the solution of only one linear system of equations per time step and does not enforce the pointwise unit-length constraint of the magnetization. While unconditional weak convergence has been analyzed in an earlier work, we now prove optimal-order convergence rates under sufficient regularity assumptions on the exact solution and the external field. In combination with our previous work, this establishes the first higher-order-in-time and linear integrator that converges both to weak and strong solutions of LLG. Numerical experiments confirm first-order convergence in space and second-order convergence in time.