Low carrier concentration crystals of the topological insulator Bi${}_{2-x}$Sb${}_x$Te${}_{3-y}$Se${}_y$: a magnetotransport study

Abstract

In 3D topological insulators achieving a genuine bulk-insulating state is an important research topic. Recently, the material system (Bi,Sb)${}_2$(Te,Se)${}_3$ (BSTS) has been proposed as a topological insulator with high resistivity and a low carrier concentration (Ren \textit{et al.} \cite{Ren2011}). Here we present a study to further refine the bulk-insulating properties of BSTS. We have synthesized Bi${}_{2-x}$Sb${}_x$Te${}_{3-y}$Se${}_y$ single crystals with compositions around $x=0.5$ and $y=1.3$. Resistance and Hall effect measurements show high resistivity and record low bulk carrier density for the composition Bi${}_{1.46}$Sb${}_{0.54}$Te${}_{1.7}$Se${}_{1.3}$. The analysis of the resistance measured for crystals with different thicknesses within a parallel resistor model shows that the surface contribution to the electrical transport amounts to 97% when the sample thickness is reduced to $1\mu$m. The magnetoconductance of exfoliated BSTS nanoflakes shows 2D weak antilocalization with $\alpha \simeq -1$ as expected for transport dominated by topological surface states.

16 pages, 6 figures, accepted for publication in New Journal of Physics

References in corpus (10)

• Non-Abelian Anyons and Topological Quantum Computation
• Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class with spin-polarized single-Dirac-cone on the surface
• A topological Dirac insulator in a quantum spin Hall phase : Experimental observation of first strong topological insulator
• Topological Surface States Protected From Backscattering by Chiral Spin Texture
• Gate-Voltage Control of Chemical Potential and Weak Anti-localization in Bismuth Selenide
• Two-dimensional Dirac fermions in a topological insulator: transport in the quantum limit
• Topological origin of subgap conductance in insulating bilayer graphene
• Bulk Band Gap and Surface State Conduction Observed in Voltage-Tuned Crystals of the Topological Insulator Bi${}_2$Se${}_3$
• Observation of Dirac Holes and Electrons in a Topological Insulator
• Emergent quantum confinement at topological insulator surfaces

Cited by in corpus (3)

• Dirac states with knobs on: interplay of external parameters and the surface electronic properties of 3D topological insulators
• Trigger of the ubiquitous surface band bending in 3D topological insulators
• Surface-state-dominated transport in crystals of the topological crystalline insulator In-doped Pb${}_{1-x}$Sn${}_x$Te