J. Meersschaut, J. Dekoster, S. Demuynck, S. Cottenier, B. Swinnen, M. Rots Journal of Magnetism and Magnetic Materials 198-199, 641-6431999A1Published while none of the authors were employed at the CMMDOI http://dx.doi.org/10.1016/S0304-8853(98)01101-9