[1] MS Ramaiah Univ Appl Sci, Fac Math & Phys Sci, Dept Phys, Bangalore 560054, Karnataka, India
[2] Indian Inst Sci, Mat Res Ctr, Bangalore 560012, Karnataka, India
[3] REVA Univ, Sch Phys Sci, Bengaluru 560064, India
[4] Tech Univ Kaiserslautern, Erwin Schrodinger Str 52, D-67663 Kaiserslautern, Germany