1. Department of Physics, Islamia College Peshawar, Peshawar 25120, Khyber Pakhtunkhwa, Pakistan
2. Department of Applied Physical and Material Sciences, University of Swat, 19200, Khyber Pakhtunkhwa, Pakistan
3. Department of Physics, University of Peshawar, Peshawar 25000, Khyber Pakhtunkhwa, Pakistan