1. Department of Physics, Cochin University of Science and Technology, Kochi 682022, Kerala, India
2. TIFR-Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research, Hyderabad 500075, India
3. Government Polytechnic College, Thirurangadi, Velimukku P.O., Malappuram 676317, Kerala, India
4. Department of Electronics, Cochin University of Science and Technology, Kochi 682022, Kerala, India
5. Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA