Advanced Micromagnetic Modeling of Recording Heads

An efficient algorithm is reported for the micromagnetic modeling of large-scale magnetic objects, such as magnetic recording heads. The numerical scheme for the solution of the Landau–Lifshitz–Gilbert (LLG) equation is a combination of the finite difference (FD), the finite element (FEM), and the fast Fourier transform (FFT) methods. The discretization of differential equation describing the magnetic body and surrounding non-magnetic domain is achieved by applying Galerkin technique. FFT is used for the calculation of boundary conditions for the magnetostatic problem. The derivation of the discrete linear operators for the fast calculation of the magnetic scalar and vector potentials is presented. Explicit integral expression for the total effective magnetic charge in the magnetic domain with non-uniform magnetization of saturation is derived. The numerical approach used in the micromagnetic software allows fast simulations of multi-scale models of recording heads on graphic processing units (GPUs) for modern recording technologies. The examples of simulations of the noise reduction in the energy assisted perpendicular magnetic recording (ePMR) head and exchange biased magnetic shield are presented.