1. Department of Condensed Matter
Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake,
Kolkata 700098, India
2. Center
for Research in Nanoscience
and Nanotechnology, University of Calcutta, Technology Campus, Block JD2, Sector III, Salt Lake, Kolkata 700
098, India
3. Applied Nuclear
Physics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar,
Kolkata 700064, India