Linear magnetoresistance, weak antilocalization and electron-hole coexistence in gate tunable topological insulator (BixSb1−x)2Te3 nanoplates

We report a systematic study on the transport properties of (Bi_0.2Sb_0.8)₂Te₃ and (Bi_0.4Sb_0.6)₂Te₃ nanoplates with a thickness of about 6 nm grown by chemical vapor deposition (CVD) on Si/SiO₂ substrate. We achieve a significant ambipolar field effect in the two samples with different compositions by applying back-gate voltage, successfully tuning the Fermi level across the Dirac point of surface states. It is found that the Hall resistance exhibits strong non-linear behavior and magnetic field induced sign change of the slope when the Fermi level is near the Dirac point, indicating the coexistence of n-type and p-type carriers. Moreover, this coincides with the striking crossover from weak antilocalization (WAL) to linear magnetoresistance (LMR). These gate and temperature dependent magneto-transport studies provide a deeper insight into the nature of LMR and WAL in topological materials.