Anomalous magneto-transport properties of epitaxial Bi$_{2}$Te$_{3}$ films grown by chemical vapor deposition (CVD)

We investigated the magneto-transport properties of Bi$_{2}$Te$_{3}$ films grown by using the chemical vapor deposition (CVD) technique. From the structural analysis using the x-ray diffractometer (XRD) and transmission electron microscope (TEM), the films were found to be highly c-axis oriented with good crystalline quality. The films were found to remain metallic down to 1.8 K with a very high carrier mobility around 30,000 cm$^{2}$/Vs despite rather high carrier concentration of about 10$^{18\, }$ (cm$^{-3})$. We investigated the behavior of the magneto-resistance (MR) under various orientations of the magnetic field ($B)$. Interestingly, it was found that the MR showed a clear oscillation signal under the in-plane $B$. In addition, the observed oscillation was quite periodic in 1/$B$ implying that the Landau quantization plays a role. As the orientation of $B$ was rotated toward the direction perpendicular to the plane, the oscillation signal disappeared and the resistance showed a very sharp decrease at low magnetic fields, which was consistent with the weak antilocalization (WAL) behavior. Those new findings are believed to be related to the nature of Bi$_{2}$Te$_{3}$ films as a topological insulator (TI) and to unveil the unexplored aspects of TIs waiting for an explanation.