1. Centre of Physics—CF-UM-UP and Laboratório de Física para Materiais e Tecnologias Emergentes (LaPMET), University of Minho, Campus of Gualtar, 4710-374 Braga, Portugal
2. Department of Physics, University of Minho, Campus of Gualtar, 4710-374 Braga, Portugal
3. Theory of Quantum Nanostructures Group, International Iberian Nanotechnology Laboratory, 4715-330 Braga, Portugal