1. Department of Physics, Faculty of Science, University of Zabol, Zabol, Iran
2. Department of Physics, Shahid Beheshti University, G. C., Evin, Tehran 19839, Iran
3. Federal University of Latin-American Integration, Technological Park of Itaipu, PO Box 2123, Foz do Iguaçu-PR 85867-670, Brazil
4. Departamento de Física, Universidade Federal de Pernambuco, Recife, PE 52171-900, Brazil