Analog simulation of flux reversal in thin magnetic films by uniform rotation

The results of an analog computer study of flux reversal in thin magnetic films are presented. The computer diagram is given for the simulation of the Landau-Lifshitz equation of motion of the magnetization vector. Solutions of these equations were obtained for pulse fields applied parallel and perpendicular to the easy axis of a film with uniaxial anisotropy. Switching curves are given which show the effect of varying the relaxation frequency λ. The switching time varies by a factor of 3 as λ is varied from 10⁸to 5 × 10⁸Hz. The various definitions of switching time which have been reported in the literature are also compared. Nonlinear resonance curves are presented for λ, values of 10⁸and 1.5 × 10⁸Hz. The curves represent solutions for the angular velocity of the magnetization when a sinusoidal field is applied perpendicular to the easy axis. For applied fields as large as half the anisotropy field the resonant frequency and linewidths are significantly different (20 percent or more) from the small signal values which are useful for determining the anisotropy field HKand the relaxation frequency λ. It is concluded that the analog technique is convenient for studying magnetic switching problems when the problems can be formulated in terms of ordinary differential equations. Other problems suitable for this approach are studies of flux reversal with various waveforms for the excitation field and of the interaction between coupled films or particles.