Low-temperature magnetoresistance hysteresis in Vanadium-doped Bi_2Te_2.4Se_0.6 bulk topological insulators

Bi_2Te_2.4Se_0.6 single crystals show gapless topological surface states and doping (x) with Vanadium allows to shift the chemical potential in the bulk band gap. Accordingly, the resistivity, carrier density, and mobility are constant below 10 K and the magnetoresistance shows weak antilocalization as expected for low-temperature transport properties dominated by gapless surface states of so-called three-dimensional topological "insulators". However, the magnetoresistance also shows a hysteresis depending on the sweep rate and the magnetic field direction. Here, we provide evidence that such magnetoresistance hysteresis is enhanced if both three-dimensional bulk states and quasi-two-dimensional topological states contribute to the transport (x = 0 and 0.03), and it is mostly suppressed if the topological states govern transport (x = 0.015). The results are discussed in terms of spin-dependent scattering between the different available states