1. Department of Physics, State University of Maringá, Maringá, PR, Brazil
2. Physics Department, Federal University of Technology of Paraná, Ponta Grossa, PR, Brazil
3. Department of Condensed Matter Physics, Aragon Institute of Nanoscience, Zaragoza, Spain
4. Physics Department, State University of Ponta Grossa, Ponta Grossa, PR, Brazil