[1] Periyar Univ, Ctr Post Grad & Res Studies, Dept Phys, Dharmapuri 635205, Tamil Nadu, India
[2] Sri Vijay Vidyalaya Coll Arts & Sci, Dept Phys, Dharmapuri 636807, Tamilnadu, India
[3] Govt Arts & Sci Coll, Dept Phys, Hosur, Tamil Nadu, India
[4] SSN Coll Engn, Ctr Crystal Growth, Dept Phys, Kalavakkam 603110, Tamil Nadu, India