1. Low Dimensional Physics Laboratory Department of Physics National Institute of Technology Mangalore 575025 Karnataka India
2. Centre for Nano Science and Engineering Indian Institute of Science Bangalore 560012 India
3. Spintronics and Vacuum Nanoelectronics Laboratory University of Cincinnati Cincinnati OH 45040 USA
4. Optoelectronics Laboratory Department of Physics National Institute of Technology Mangalore 575025 Karnataka India
5. Materials and Catalysis Laboratory Department of Chemistry National Institute of Technology Mangalore 575025 Karnataka India