Effect of Sb substitution on the topological surface states in Bi₂Se₃ single crystals: A magneto-transport study

Magneto-transport measurements have been carried out on Bi₂-_xSb_xSe₃ (x = 0,0.05, 0.1,0.3,0.5) single crystals at 4.2 K temperature in the magnetic field range of - 15 T to 15 T. Shubnikov-de Haas (SdH) oscillations of 2D nature were observed in samples with Sb concentration upto x = 0.3. The analyses of SdH oscillations observed in magneto-resistance data using Lifshitz-Kosevich equation reveal a systematic decrease in the Fermi surface area with Sb substitution. The Berry phase obtained from the Landau level fan diagram suggests the occurrence of 2D oscillations arising from a topological surface state (TSS) for Sb concentrations of x = 0,0.05 and 0.1; while 2D oscillation seen at higher Sb concentration is attributed to surface 2D electron gas consequent to downward band bending.