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