1. School of Advanced Sciences, Vellore Institute of Technology, Vellore 632014, India
2. Dept. of Physics, G.T.N Arts College (Affiliated to Madurai Kamaraj University), Madurai, Tamil Nadu 625021, India
3. Functional Nanomaterials and Devices Lab, SASTRA Deemed to be University, Thanjavur 613401, India
4. Centre for Nanotechnology Research, Vellore Institute of Technology, Vellore 613401, India