Weak localization and anti-localization in rare earth doped topological insulators

TL;DR

This study investigates how rare-earth doping affects magneto-transport in topological insulators, revealing a controllable transition between weak localization and anti-localization linked to surface state gap opening.

Contribution

It demonstrates that rare-earth doping can manipulate the magneto-transport properties and surface state gaps in topological insulators, providing a new method for tuning their electronic behavior.

Findings

Doping induces a crossover from weak anti-localization to weak localization.

Surface state gap opening correlates with the localization transition.

Rare-earth doping enables control over topological surface states.

Abstract

We study magneto-transport phenomena in two rare-earth doped topological insulators, SmxFexSb2-2xTe3 and SmxBi2-xTe2Se single crystals. The magneto-transport behaviours in both compounds exhibit a systematic crossover between weak anti-localization (positive magnetoresistance) and weak localization (negative magnetoresistance) with changes in temperatures and magnetic fields. The weak localization is caused by rare-earth-doping induced magnetization, and the weak anti-localization originates from topologically protected surface states. The transition between weak localization and weak anti-localization demonstrates a gap opening at the Dirac point of surface states in the quantum diffusive regime. This work demonstrates an effective way to manipulate the magneto-transport properties of the topological insulators by rare-earth element doping. Magnetometry measurements indicate that the Sm-dopant alone is paramagnetic, whereas the co-doped Fe-Sm state has short-range antiferromagnetic order. Our results hold potential for the realization of exotic topological effects in gapped topological insulator surface states.