Magnetization reversal in thin magnetic films with perpendicular anisotropy

摘要

A one‐dimensional theory of magnetization reversal in thin, perpendicularly anisotropic magnetic films is presented. It is postulated that the presence of a defective point creates an infinitely deep, infinitely narrow potential well which inhibits the rotation of local magnetization. The interval D between neighboring defects, the saturation magnetization Ms, the anisotropy constant Ku, and the exchange energy constant A are assumed to be finite and uniform across the film. Starting with an initial state where the film is uniformly magnetized to saturation in the easy direction, we show that a discontinuous change of state occurs when the reverse external field H reaches a critical value Hc. The domains thus nucleated at the critical field expand to cover the entire area of the film as H increases beyond Hc. Using the normalized values of H and D, defined, respectively, as h = H/(2Ku/Ms) and d = D/(4A/Ku)1/2, we show that the critical field hc is a function only of d and that its value decreases significantly as d increases.