Ultrafast precessional switching in a permalloy thin film with magnetic surface anisotropy.

Analytical and numerical analysis of ultrafast precessional switching dynamics, in a uniformly magnetized anisotropic permalloy thin film, described by the Landau-Lifshitz (LL) equation is presented. Precessional switching is realized in the film by applying a uniform pulsed magnetic field normal to the easy axis of magnetocrystalline anisotropy. The analytical solution of the LL equation is expressed in terms of the Jacobi elliptic function, the period of which is related to the period of the precessional motion. It is shown that switching occurs in the film above a critical value of the applied field. The switching time decreases steadily when the strength of the applied magnetic field is increased and further it reduces significantly when the film has magnetic surface anisotropy in it.