Influence of the biquadratic interlayer coupling in the specific heat of Fibonacci magnetic multilayers

A theoretical study of the specific heat C(T) as a function of temperature in Fibonacci magnetic superlattices is presented. We consider quasiperiodic structures composed of ferromagnetic films, each described by the Heisenbe rg model, with biquadratic and bilinear coupling between them. We have take n the ratios between the biquadratic and bilinear exchange terms according to experimental data recently measured for different regions of their regim e. Although, some previous properties of the spin-wave specific heat are al so reproduced here, new features appear in this case, the most important of them being an interesting broken symmetry related to the interlayer biquad ratic term. (C) 2001 Elsevier Science B.V. All rights reserved.