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Micromagnetic Modelling. Total free energy. Conditions. Total effective field. . “Torque condition” static equilibrium. Energy minimization using a variational principle. Landau-Lifshitz-Gilbert equation. - M X (M X H ). H. - (M X H ). M. h z. h y. h x. Discretization.
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Micromagnetic Modelling Total free energy Conditions Total effective field “Torque condition” static equilibrium Energy minimization using a variational principle Landau-Lifshitz-Gilbert equation - M X (M X H) H - (M X H) M
hz hy hx Discretization Ferromagnetic System N x X Ny X Nz rectangular cells Approximations : - uniform magnetized cells -Neumann boundary condition on the free surface Stable state reached if:
+ + + + + + + + + + + + - - - - - - - - - - - - - - Stray field evaluation R(i-i’,j-j’,k-k’) uniform magnetized cells only surface charges Volume Magnetic charges Surface demagnetization tensor Convolution theorem -FFT implementation