1. Department of Physics and Electronics, CHRIST (Deemed to be University), Bangalore 560029, India
2. Materials Research Centre, Indian Institute of Science, Bangalore 560012, India
3. Nanoscience Laboratory, Department of Physics, National Institute of Technology, Durgapur 713209, West Bengal, India
4. Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur 721302, West Bengal, India