Indications of the topological transport by the universal conductance fluctuations in the Bi2Te2Se microflakes

TL;DR

This study observes universal conductance fluctuations in Bi2Te2Se microflakes, providing evidence for topological surface states through magnetoresistance measurements and analysis of fluctuation amplitudes.

Contribution

It demonstrates the topological origin of conductance fluctuations in Bi2Te2Se microflakes, confirming the role of surface electrons and aligning with theoretical predictions.

Findings

UCFs are observed in Bi2Te2Se microflakes.

UCF amplitudes remain unchanged under in-plane magnetic fields.

Intrinsic UCF magnitude exceeds 0.37 e2/h, consistent with topological surface states.

Abstract

Universal conductance fluctuations (UCFs) are extracted in the magnetoresistance responses in the bulk-insulating Bi2Te2Se microflakes. Its two-dimensional character is demonstrated by the field-tilting magnetoresistance measurements. Its origin from the surface electrons is determined by the fact that the UCF amplitudes keep unchanged while applying an in-plane field to suppress the coherence of bulk electrons. After considering the ensemble average in a batch of micrometer-sized samples, the intrinsic UCF magnitudes of over 0.37 e2/h is obtained. This agrees with the theoretical prediction on topological surface states. All the evidence point to the successful observation of the UCF of topological surface states.