PHASE-TRANSITIONS IN ANISOTROPIC MAGNETIC SUPERLATTICES

The paper reports a theoretical study of phase transitions in antiferr omagnetic superlattices. The boundaries of stability of the ferro-and antiferromagnetic phases have been calculated by a model taking into a ccount the layered structure of these materials. The expressions obtai ned are precise in the limit of a large number of layers. In the case of a small number of layers, the problem reduces to a simple numerical procedure of solving a transcendental equation. The critical field is shown to depend substantially on the biquadratic non-Heisenberg excha nge constant. (C) 1997 American Institute of Physics.