Electrical transport studies of Topological Insulator Bi$_{2}$Te$_{3}$ Nanotubes

We have studied electrical transport properties of candidate topological insulator Bismuth Telluride (Bi$_{2}$Te$_{3})$ nanotubes. Bi$_{2}$Te$_{3}$ nanotube samples were synthesized by solution phase method, with the outer diameters in the range of 70$\pm $5 nm and inner diameter 50$\pm $5 nm and the length of 3 to 10 um. Platinum contact leads were fabricated on the nanotubes by focusing ion beam assisted deposition. Electrical transport measurements were conducted at low temperatures and high magnetic fields (up to 9T). The nanotubes showed good insulating behavior in comparison with the thin films which are often metallic. Resistance oscillation as a function of magnetic field was observed when the magnetic field is applied parallel to the nanotubes. The periods range from 6000 Oe to 8350 Oe, which correspond to the diameter of 80 to 100 nm according to Aharonov-Bohm oscillation formula. This is close but slightly larger than the outer diameter of the nanotubes. The amplitude of the oscillations decays rapidly as field increases, possibly due to scattering. When the magnetic field was applied perpendicular to the nanotube, no resistance oscillation was observed. The possible origins of the oscillation effect will be discussed.