Emerging conduction pathways in semiconducting bismuth-antimony alloys

As strong topological insulators, Bi1-xSbxalloys with ∼ 0.07 < x < 0.22 are predicted to host topologically protected conduction pathways along extended defects, such as dislocations. Due to the presence of bulk conduction, these fascinating topological features have been obscured to date. We examine carrier transport and electronic states in high-purity single-crystals of Bi1-xSbxalloys with 11 at% Sb. Using high magnetic fields, we suppress bulk conduction, enabling the identification of the residual conductivity associated with extended defects. A two-band analysis of magnetotransport measurements, in combination with angle-resolved photoemission spectroscopy, reveals a bandgap ≥ 40 meV, larger than Arrhenius analyses of temperature-dependent resistivities. With mobility as high as 750 000 cm²V⁻¹s⁻¹, Bi-Sb alloys are promising candidates for topological electronics and related applications.