Abstract:
We have investigated the transport properties of topological insulator based on single-crystal
Bi0.83Sb0.17 nanowires. The single-crystal nanowire samples in the diameter range 200 nm – 1.1 μm were
prepared by the high frequency liquid phase casting in a glass capillary using an improved Ulitovsky
technique; they were cylindrical single-crystals with (1011) orientation along the wire axis. In this orientation,
the wire axis makes an angle of 19.5o with the bisector axis C1 in the bisector-trigonal plane. Bi0.83Sb0.17 is a
narrow gap semiconductor with energy gap at L point of Brillouin zone ΔE= 21 meV. In accordance with the
measurements of the temperature dependence of the resistivity of the samples resistance increases with
decreasing temperature, but at low temperatures decrease in the resistance is observed. This effect, decrease
in the resistance, is a clear manifestation of the interesting properties of topological insulators - the presence
on its surface of a highly conducting zone. The Arrhenius plot of R in samples d=1.1 μm and d=200 nm
indicates a thermal activation behavior with an activation gap ΔE= 21 and 40 meV, respectively, which
proves the presence of the quantum size effect in these samples. We found that in the range of diameter 1100
nm - 200 nm when the diameter decreases the energy gap is growing exponentially. We have investigated
magnetoresistance of Bi0.83Sb0.17 nanowires at various magnetic field orientations. From the temperature
dependences of Shubnikov de Haas oscillation amplitude for different orientation of magnetic field we have
calculated the cyclotron mass mc and Dingle temperature TD for longitudinal and transverse (B||C3 and
B||C2) directions of magnetic fields, which equal 1.96*10-2 m0, 9.8 K, 8.5*10-3 m0 , 9.4 K and 1.5*10-1 m0 , 2.8 K
respectively. The observed effect are discussed.