1. Institute of Science, Nirma University, Ahmedabad 382481, Gujarat, India
2. Department of Applied Physics, Faculty of Technology and Engineering, The M. S. University of Baroda, Vadodara 390001, Gujarat, India
3. Institute of Technology, Nirma University, Ahmedabad 382481, Gujarat, India
4. Department of Physics, Faculty of Science, The M. S. University of Baroda, Vadodara 390002, Gujarat, India