1. Department of Physics, Pondicherry University, Puducherry 605014, India
2. UGC-DAE CSR, Kalpakkam Node, Kokilamedu 603104, India
3. Institut für Mineralogie, Westfälische Wilhelms-Universität, Corrensstraße 24, 48149 Münster, Germany
4. Advanced Functional Materials Laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli 620 015, India
5. Department of Materials Science and Engineering, Hubei University, Wuhan 430062, China
6. Physics Department, Oakland University, Rochester, Michigan 48309, USA