Field-induced magnetic reorientation in ultrathin ferromagnetic films: Phase diagrams

The magnetic reorientation, transition can be induced by applying an external transverse magnetic field. The magnetic field at, which the magnetization reaches the field direction is called the reorientation magnetic field. The reorientation magnetic field in ultrathin ferromagnetic films is studied within the framework of the many body Green function theory. The model Hamiltonian includes a Heisenberg term with different surface exchange couplings with respect to the bulk one, a second-order single ion anisotropy, and a transverse external magnetic field in the x-direction. The single-ion anisotropy term is treated by the generalized Anderson-Callen decoupling scheme. We investigate the reorientation magnetic field h(OR)(x) as a function of the surface single-ion anisotropic parameter K(2S)(T --> 0) for different: film thicknesses L, surface exchange coupling enhancements Delta(s), temperatures, T and as a function of the temperature for different film thicknesses L. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim