Two-dimensional universal conductance fluctuations and the electron-phonon interaction of topological surface states in Bi2Te2Se nanoribbons

TL;DR

This study provides experimental evidence of two-dimensional universal conductance fluctuations in topological insulator nanoribbons, revealing the role of electron-phonon interactions and bulk carrier dephasing in surface state transport.

Contribution

First demonstration of 2D UCFs in topological insulator surface states, isolating surface effects from bulk conductance in Bi2Te2Se nanoribbons.

Findings

UCFs are solely perpendicular to magnetic field direction

Surface transport confirmed by weak antilocalizations

Electron-phonon interaction influences surface state dephasing

Abstract

The universal conductance fluctuations (UCFs), one of the most important manifestations of mesoscopic electronic interference, have not yet been demonstrated for the two-dimensional surface state of topological insulators (TIs). Even if one delicately suppresses the bulk conductance by improving the quality of TI crystals, the fluctuation of the bulk conductance still keeps competitive and difficult to be separated from the desired UCFs of surface carriers. Here we report on the experimental evidence of the UCFs of the two-dimensional surface state in the bulk insulating Bi2Te2Se nanoribbons. The solely-B\perp-dependent UCF is achieved and its temperature dependence is investigated. The surface transport is further revealed by weak antilocalizations. Such survived UCFs of the topological surface states result from the limited dephasing length of the bulk carriers in ternary crystals. The electron-phonon interaction is addressed as a secondary source of the surface state dephasing based on the temperature-dependent scaling behavior.