1. Institute of Physics, Bhubaneswar-751005, Orissa, India
2. Government Women's College, Berhampur (Ganjam), Orissa, India
3. Department of Physics, G.M. College (Autonomous), Sambalpur-768004, Orissa, India
4. Theoretische Tieftemperature Physik, Gerhard–Mercator University, Duisburg 47049, Duisburg, Germany