1. Department of Physics, School of Natural Sciences, Shiv Nadar University, NH-91, Greater Noida, Uttar Pradesh 201314, India
2. Nanotechnology and Integrated Bioengineering Centre, University of Ulster, Jordanstown Campus, Newtownabbey, Northern Ireland BT37 0QB U.K.
3. Department of Condensed Matter Physics and Material Sciences, S N Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India