SCALING OF THE EXCHANGE INTERACTIONS IN CO CU MULTILAYERS WITH TEMPERATURE/

We have measured the temperature dependence of the exchange coupling i n Co/Cu multilayers grown at the first antiferromagnetic maximum. Both clean samples displaying good bilinear coupling, and samples with dam aged spacers exhibiting strong biquadratic coupling were investigated. We found that rather than obeying a Bloch law, between 5 and 300 K th e saturation magnetisation falls as T-2 for the antiferromagnetic samp le. and like T-3 for the biquadratic sample, consistent with theoretic al predictions. The normalised magnetisation loop was independent of t emperature for both samples, neither the saturation field nor the rema nent fraction vary throughout the entire temperature range. We interpr et this data as showing that the saturation magnetisation, bilinear an d biquadratic coupling constants share a common temperature dependence . The exact causes of this scaling behaviour remain unclear. (C) 1998 Elsevier Science B.V. All rights reserved.