1. Department of Physics, Karpagam Academy of Higher Education, Coimbatore 641021, India
2. Department of Mechanical Engineering, Keimyung University, Daegu 42601, Republic of Korea
3. Micro-Nano System Centre, Tyndall National Institute, University College Cork, T12R5CP Cork, Ireland
4. Department of Physics, Karpagam College of Engineering, Coimbatore 641032, India