[1] SRM Inst Sci & Technol, Dept Phys, Ramapuram Campus, Chennai 600089, Tamil Nadu, India
[2] Presidency Coll Autonomous, Dept Phys, Chennai 600005, Tamil Nadu, India
[3] Thiru Kolanjiappar Govt Arts Coll, Dept Phys, Vriddhachalam 606001, Tamil Nadu, India