Field-driven reorientation in ultrathin ferromagnetic films with uniaxial anisotropy

The field-driven spin reorientation transition in uniaxial in-plane magneti zed films is discussed by means of phase diagrams which are obtained from t he stability analysis of the thermodynamical potential. A classification of the field induced reorientation is carried out concerning the anisotropy a xes in films grown on vicinal and twofold low-index surfaces. It is shown t hat hard-axis loops with magnetization flop are directly related to the reo rientation in field. In the framework of the general theory the hard-axis l oops can be precisely analyzed.