1. Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
2. Centre for Research in Nano-Technology and Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
3. Materials Theory Division, Department of Physics and Astronomy, Uppsala University, Uppsala SE-75120, Sweden
4. Department of Electrical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
5. Department of Metallurgical Engineering and Material Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India