[1] Indian Inst Technol, Dept Phys, Condensed Matter Low Dimens Syst Lab, Kanpur 208016, Uttar Pradesh, India
[2] Indian Inst Sci, Solid State & Struct Chem Unit, Bangalore 560012, Karnataka, India
[3] Indian Assoc Cultivat Sci, Ctr Adv Mat, Kolkata 700032, India