1. i3N and Department of Physics, University of Aveiro, 3810-193 Aveiro, Portugal
2. CENIMAT, Department of Materials Science, School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal
3. CENIMAT/i3N, Department of Physics, School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal