Surface states induced weak anti-localization effect in Bi0.85Sb0.15 topological single crystal

Abstract

We report, an experimental evidence of surface states (SS) driven magneto-transport in a Bi _0.85 Sb _0.15 single crystal. Detailed high field (up to 12T) and low temperature (down to 2 K) magneto-transport measurements are been carried out on the studied Bi _0.85 Sb _0.15 single crystal. The phase, composition and Raman modes are studied through x-ray diffraction, Energy dispersive x-ray, and Raman spectroscopy. The obtained crystal shows non-saturating magnetoresistance (≈ 4250%) at 2 K and 12T, along with the existence of weak-anti localization (WAL) effect at around zero magnetic field. Further, the Hikami-Larkin-Nagaoka (HLN) analysis is performed to analyse the WAL effect. The prefactor ( α ) and phase coherence length ( L _φ _) are deduced at various temperatures, which signified the presence of more than one conduction channel in the studied Bi _0.85 Sb _0.15 single crystal. The effect of quantum scattering, bulk contribution from underneath the surface states and defects are been studied by adding various field dependent quadratic, linear and constant terms to the SS driven HLN equation. Various possible scattering mechanism are studied by analysing the temperature dependence of the phase coherence length. Angle dependent magneto-conductivity of the studied Bi _0.85 Sb _0.15 single crystal clearly confirmed the surface states dominated transport in present crystal.

Keywords

• topological insulator
• magnetoresistance
• phase coherence length
• Kohler’s rule
• Hikami-Larkin-Nagaoka model
• quantum scattering