1. Indian Institute of Technology (BHU), Varanasi 221005, India
2. Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India
3. S. N. Bose National Centre for Basic Sciences, Kolkata 700098, India
4. Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
5. Banaras Hindu University, Varanasi 221005, India