Defect induced negative magnetoresistance and surface state immunity in topological insulator BiSbTeSe2

TL;DR

This study reveals that defects induce negative magnetoresistance in BiSbTeSe2 while surface states remain unaffected, demonstrating robustness of topological surface states against disorder at low temperatures.

Contribution

It demonstrates that defect-induced disorder causes negative magnetoresistance in BiSbTeSe2 without impairing its topological surface states.

Findings

Negative magnetoresistance appears below 50 K due to defect states.

Surface states remain unaffected by disorder.

Negative magnetoresistance decreases with increasing temperature.

Abstract

Absence of backscattering and occurrence of weak anti-localization are two characteristic features of topological insulators. We find that the introduction of defects results in the appearance of a negative contribution to magnetoresistance in the topological insulator BiSbTeSe2, at temperatures below 50 K. Our analysis shows that the negative magnetoresistance originates from an increase in the density of defect states created by introduction of disorder, which leaves the surface states unaffected. We find a decrease in the magnitude of the negative magnetoresistance contribution with increasing temperature and a robustness of the topological surface states to external disorder.