Enhanced linear magneto-resistance near the Dirac point in topological insulator Bi₂(Te_1-xSe_x)₃ nanowires

We report the composition and back-gate voltage tuned transport properties of ternary compound Bi₂(Te_1-xSe_x)₃ nanowires synthesized by chemical vapor deposition (CVD). It is found that the population of bulk carriers can be suppressed effectively with increasing the Se concentration x. In Bi₂(Te_1-xSe_x)₃ nanowires with x = 25% ± 5%, the ambipolar surface conduction associated with tuning the Fermi energy across the Dirac point of topological surface states is induced by applying a back-gate voltage. Importantly, we find that while the magneto-resistance (MR) follows the weak antilocalization (WAL) behavior when the Fermi level is tuned away from the Dirac point, MR is enhanced in magnitude and turns more linear in the whole magnetic field range (between ±9 T) near the Dirac point. The observation of the enhanced linear magneto-resistance (LMR) and crossover from WAL to LMR, near the Dirac point provides a deeper insight into understanding the nature of topological insulator’s surface transport and the relation between these two widely observed magneto-transport phenomena.