THEORETICAL INVESTIGATION OF TEMPERATURE-INDUCED PHASE-TRANSITION IN EXCHANGE-COUPLED DOUBLE-LAYERS

In the present work the mean field theory is used to determine the mag netic properties of a GdCo ''planar'' layer under exchange interaction with a TbFeCo ''perpendicular'' layer. The magnetization distribution s phi(1) and phi(2) in the planar and perpendicular layers are determi ned from a micromagnetic model using a variational method of the magne tic energies in the temperature range 0-500 K. phi(2) presents small c hange with the temperature. On the other hand, phi(1) and its mean val ue [phi(1)] are very sensitive to the temperature and the layer compos ition and thickness. A temperature induced phase transition with a mag netization reorientation from in-plane to a perpendicular direction ca n be induced in the planar layer in a temperature window Delta T which depends on its compensation temperature T-CP1 and its thickness which has to be lower than a critical value. (C) 1997 American Institute of Physics.