1. Department of Physics, Aligarh Muslim University, Aligarh 202002, India
2. Department of Physics and Electronics, Dr. Ram Manohar Lohia Avadh University, Faizabad 224001, India
3. Department of Physics, Banaras Hindu University, Varanasi 221005, India
4. Department of Applied Physics, Aligarh Muslim University, Aligarh 202002, India