1. Magnetic Materials Laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli 620 015, India
2. High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
3. Institut des Molécules et Matériaux du Mans IMMM UMR CNRS 6283, Université du Maine, Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France