1. Centro/Departamento
de Física, Universidade do Minho, 4710-057 Braga, Portugal
2. International Iberian Nanotechnology Laboratory, Av. Mestre José Veiga, 4715-330 Braga, Portugal
3. Nanomag Laboratory, Department of Applied Physics, Technological
Research Institute, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain