1. Advanced Functional Materials Laboratory, Department of Physics, Tezpur University (Central University), Tezpur, 784028, India
2. Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
3. Benjamin M. and Mary Greenwood Anderson Professor of Engineering, Department of Materials Science and NanoEngineering, Rice University, 6100 Main Street, Houston, Texas 77005, USA