1. Centre of Advanced Study, Department of Metallurgical Engineering, Indian Institute of Technology, Banaras Hindu University, Varanasi 221005, India
2. Department of Physics, Indian Institute of Technology, Banaras Hindu University, Varanasi 221005, India
3. Centre of Advanced Study, Department of Metallurgical Engineering, Indian Institute of Technology, Banaras Hindu University, Varanasi 221005, India e-mail: ;
4. Department of Mechanical Engineering, Indian Institute of Technology, Banaras Hindu University, Varanasi 221005, India