Linear magneto-resistance versus weak antilocalization effects in Bi$_2$Te$_3$ films

TL;DR

This study investigates the magneto-resistance effects in Bi2Te3 topological insulator films, distinguishing between weak antilocalization and classical linear MR effects across different transport regimes.

Contribution

It clarifies how to separate classical linear MR from quantum WAL effects in Bi2Te3 films, improving the interpretation of MR measurements in topological insulators.

Findings

WAL dip is prominent in higher resistivity samples.

Classical linear MR must be separated from WAL for accurate analysis.

Incorrect WAL fitting can lead to unrealistic parameters.

Abstract

In chalcogenide topological insulator materials, two types of magneto-resistance (MR) effects are widely discussed: a positive MR dip around zero magnetic field associated with the weak antilocalization (WAL) effect and a linear MR effect which generally persists to high fields and high temperatures. We have studied the MR of topological insulator Bi2Te3 films from the metallic to semiconducting transport regime. While in metallic samples, the WAL is difficult to identify due to the smallness of the WAL compared to the samples' conductivity, the sharp WAL dip in the MR is clearly present in the samples with higher resistivity. To correctly account for the low field MR by the quantitative theory of WAL according to the Hikami-Larkin-Nagaoka (HLN) model, we find that the classical (linear) MR effect should be separated from the WAL quantum correction. Otherwise the WAL fitting alone yields an unrealistically large coefficient $\alpha$ in the HLN analysis.