1. Department of Metallurgical and Material Engineering, Jadavpur University, Kolkata 700032, India
2. UGC-DAE Consortium for Scientific Research, Kolkata Centre, III/LB-8, Bidhannagar, Kolkata 700 098, India
3. Thin Film and Nanoscience Laboratory, Department of Physics, Jadavpur University, Kolkata 700032, India