1. Laboratory for Low Dimensional Materials, Institute of Physics, Bhubaneswar 751005, India
2. Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
3. Computational Materials and Nanoscience Group, Department of Physics and Electronics, St. Xavier’s College, Ahmedabad 380009, India
4. Department of Microtechnology and Nanoscience, Chalmers University of Technology, Göteborg SE-41296, Sweden
5. Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala S-75120, Sweden
6. Applied Materials Physics, Department of Materials and Engineering, Royal Institute of Technology (KTH), Stockholm S-100 44, Sweden