1. Physics Department, Faculty of Science, Sohag University, Sohag-82524, Egypt
2. Leibniz Institute of Solid State and Material Research Dresden, P. O. Box 270016, D-01171 Dresden, Germany
3. Physics Department, King Fahd University of Petroleum & Minerals, KFUPM Box 5047, Dhahran 31261, Saudi Arabia
4. Physics Department, College of Science & Arts, Najran University, P. O. 1988, Najran, Saudi Arabia