1. Physics Centre of Minho and Porto Universities (CF-UM-UP), University of Minho, Braga 4710-057, Portugal
2. LaPMET - Laboratory of Physics for Materials and Emergent Technologies, University of Minho, Braga 4710-057, Portugal
3. Physics Department, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte 59078-900, Brazil
4. CMEMS-UMinho - Center for Microelectromechanical Systems, University of Minho, Campus de Azurém, Guimarães 4800-058, Portugal