1. Department of Physics, State University of Maringá, Maringá, PR, Brazil
2. Department of Physics, Federal University of Paraná, Jandaia do Sul, PR, Brazil
3. Department of Physics, State University of the West-Center (Unicentro), Guarapuava, PR, Brazil
4. Department of Electrical and Computer Engineering, University of Texas at San Antonio, San Antonio, TX, USA