1. Department of Physics, National Institute of Technology Durgapur, Durgapur 713209, India
2. Department of Physics, Kulti College, Kulti 713343, India
3. Technische Universitaet Darmstadt, Materials Science, 64287 Darmstadt, Germany
4. The National Institute of Advanced Industrial Science and Technology (AIST), 807-1 Shuku-machi, Tosu, Saga 841-0052, Japan