1. Department of Condensed Matter and Materials Physics, S. N. Bose National Centre for Basic Sciences, Sector III, Block JD, Salt Lake, Kolkata 700106, India
2. Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, 121 16, Prague 2, Czech Republic
3. Department of Chemistry, Jadavpur University, Kolkata-700032, India
4. Department of Physics, Indian Institute of Technology Patna, Bihar-801106, India