1. Department of Physics, Banaras Hindu University, Varanasi 221005, India
2. Department of Physics, Ewing Christian College, Allahabad 211003, India
3. Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
4. Department of Physics, Kumaun University, Nainital 263001, India
5. Department of Physics, Institute of Science, Banaras Hindu University, Varanasi 221005, India
6. Department of Physics, School of Physical and Chemical Science, Central University of South Bihar, Gaya 428236, Bihar, India