1. Department of Physics, Federal University of Espírito Santo, Vitória, Espírito Santo 29075-910, Brazil
2. Departamento de Física de la Materia Condensada, Instituto Nicolás Cabrera (INC), Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain
3. Institute of Physics, Federal University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro 21941-972, Brazil
4. Brazilian Nanotechnology National Laboratory (LNNano), CNPEM, Campinas, São Paulo 13083-970, Brazil
5. Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
6. Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States