# Low carrier concentration crystals of the topological insulator Bi2-xSbxTe3-ySey: a magnetotransport study

Y. Pan, D. Wu, J.R. Angevaare, H. Luigjes, E. Frantzeskakis, N. de Jong, E. van Heumen, T.V. Bay, B. Zwartsenberg, Y. Huang, M. Snelder, A. Brinkman, M.S. Golden, A. de Visser

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## 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 et al 2011 Phys. Rev. B 84 165311). Here we present a study to further refine the bulk-insulating properties of BSTS. We have synthesized BSTS 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 μm. The magnetoconductance of exfoliated BSTS nanoflakes shows 2D weak antilocalization with $\alpha \simeq -1$ as expected for transport dominated by topological surface states.
Original language English 123035 15 New journal of physics 16 https://doi.org/10.1088/1367-2630/16/12/123035 Published - 2014

• METIS-309403
• IR-94525

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