1. Centre of Excellence in Solid State Physics, University of the Punjab, Quid-e-Azam Campus, Lahore-54590, Pakistan.
2. Department of Physics, The University of Lahore, Lahore-54590, Pakistan.
3. Department of Physics, University of Malakand Chakdara, Lower Dir 18800, Pakistan.
4. Department of Physics, COMSATS Institute of Information Technology, Defence Rd., Lahore-54000, Pakistan.