Seminarium Międzynarodowego Laboratorium Silnych Pól Magnetycznych i Niskich Temperatur PAN
ul. Gajowicka 95, sala seminaryjna (nowy budynek, II piętro)
Quantum Oscillations in Topological Insulator Bi0.83Sb0.17 Nanowires
L. Konopko, A. Nikolaeva
Ghitu Institute of Electronic Engineering and Nanotechnologies, Academy of Sciences of Moldova, Chisinau, Moldova
We investigate the transport properties of topological insulator (TI) Bi0.83Sb0.17 nanowires. Single-crystal nanowire samples with diameters ranging from 75 nm to 1.1 μm are prepared using high frequency liquid phase casting in a glass capillary; cylindrical single crystals with (1011) orientation along the wire axis are produced. Bi0.83Sb0.17 is a narrow-gap semiconductor with an energy gap at the L point of the Brillouin zone, ΔE = 21 meV. We investigate the magnetoresistance of Bi0.83Sb0.17 nanowires at various magnetic field orientations. Shubnikov-de Haas oscillations are observed in Bi0.83Sb0.17 nanowires at T = 1.5 K, demonstrating the existence of high mobility (μS = 26,700−−47,000 cm2V-1s-1) two-dimensional (2D) carriers in the surface areas of the nanowires, which are nearly perpendicular to the C3 axis. In thin Bi0.83Sb0.17 nanowires (d ≤ 100 nm) at low temperatures (1.5 K ≤ T < 5 K), we discovered the Aharonov–Bohm (AB) oscillations of longitudinal magnetoresistance with a period of one flux quantum, Φ0 (ΔB =Φ0/S, where S is the cross-sectional area of the nanowire). The period ΔB depends on the inclination angle α of the magnetic field according to the law ΔB=ΔBparallel/cosα. This law is preserved up to angles of about 60 degrees. The non monotonic changes of magnetoresistance, which are equidistant in a direct magnetic field, were observed in transverse magnetic fields under conditions where the magnetic flux through the cylinder Φ = 0. Possible reasons for this behavior by analogy with thin bismuth nanowires are discussed.
The information on the implementation of the joint STCU project #5986 “Development of anisotropic thermoelectric devices based on semimetal microwires” and plans for the future will be provided.
