Linear magnetoresistance versus weak antilocalization effects in Bi2Te3

In chalcogenide topological insulator materials, two types of magnetoresistance (MR) effects are widely discussed: a sharp MR dip around zero magnetic field, associated with the weak antilocalization (WAL) effect, and a linear MR (LMR) effect that generally persists to high fields and high temperatures. We have studied the MR of thin films of the topological insulator Bi2Te3 from the metallic to semiconducting transport regime. In the metallic samples, the WAL is difficult to identify owing to the low magnitude of the WAL compared to the samples' conductivity. Furthermore, the sharp WAL dip in the MR is clearly present in samples with a higher resistivity. To correctly account for the low-field MR with the quantitative theory of the WAL according to the Hikami-Larkin-Nagaoka (HLN) model, we find that the classical (linear) MR effect should be taken into account in combination with the WAL quantum correction. Otherwise, the WAL fitting alone yields an unrealistically large coefficient alpha in the HLN analysis. This work clarifies the WAL and LMR as two distinct effects and offers an explanation for the overly large alpha in the WAL analysis of topological insulators in some studies.