1. Department of Physics, Hemvati Nandan Bahuguna Garhwal University (A Central University), Garhwal, Srinagar, Uttarakhand 246174, India
2. Department of Energy Science and Engineering, Indian Institute of Technology (IIT) Delhi, New Delhi 110016, India
3. Center for Nanoscience and Nanotechnology, Jamia Millia Islamia, New Delhi 110025, India
4. Department of Physics, Zakir Hussain Delhi College, Jawahar Lal Nehru Marg, New Delhi 110002, India