1. Departamento de Física, Universidade Federal da Paraíba, Caixa Postal 5008, CEP 58.059-970 João Pessoa, Pb, Brazil
2. Research and Innovation Enterprise "Modus," Zagorodnoye shosse 8/7, Box 49, Moscow, 113152, Russia
3. North-West Polytechnical Institute, Department of Physics, Millionnaya str. 5, 191065, St. Petersburg, Russia