1. Institut des Matériaux Jean Rouxel (IMN)-UMR6502, Université de Nantes, CNRS; 2 rue de la Houssinière, BP 32229 44322 Nantes Cedex 3 France
2. INL - International Iberian Nanotechnology Laboratory; Av. Mestre José Veiga s/n, 4715-330 Braga Portugal
3. Departamento de Física, Universidade Federal de Minas Gerais; Belo Horizonte, 31270-901 Brazil
4. Faculty of Physics, Warsaw University of Technology; Koszykowa 75 00-662 Warszawa Poland
5. Laboratoire Charles Coulomb (L2C)- UMR 5221, Université Montpellier, CNRS; Montpellier, 34095 France