1. International and Inter University Centre for Nanoscience and Nanotechnology, Mahatma Gandhi University, Kottayam 686 560, Kerala, India
2. School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam 686 560, Kerala, India
3. School of Nanoscience and Nanotechnology, Mahatma Gandhi University, Kottayam 686 560, Kerala, India
4. High Pressure & Synchroton Radiation Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
5. Homi J Bhabha National Institute, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India