1. Departamento de Física, Universidade Federal do Maranhão, São Luís 65085-580, MA, Brazil
2. Unidade Educacional de Penedo, Campus Arapiraca, Universidade Federal de Alagoas, Av. Beira Rio, s/n—Centro Histórico, Penedo 57200-000, AL, Brazil
3. Faculty of Physics, Shahrood University of Technology, Shahrood P.O. Box 3619995161-316, Iran
4. Department of Physics, University of Hradec Králové, Rokitanského 62, 500 03 Hradec Králové, Czech Republic