B. Swinnen, J. Dekoster, J. Meersschaut, S. Demuynck, S. Cottenier, G. Langouche, M. Rots Journal of Magnetism and Magnetic Materials 175 (1-2), 23-321997A1Published while none of the authors were employed at the CMMDOI http://dx.doi.org/10.1016/S0304-8853(97)00154-6