1. i3N, Department of Physics, University of Aveiro, 3810-193 Aveiro, Portugal
2. CICECO, Department of Materials and Ceramic Engineering, University of Aveiro, 3810-193 Aveiro, Portugal
3. INL – International Iberian Nanotechnology Laboratory, 4715-330 Braga, Portugal
4. CIETI, Department of Physics, ISEP – Porto School of Engineering, 4200-072, Portugal