Quasi-ballistic transport of Dirac fermions in a Bi2Se3 nanowire

TL;DR

This study investigates quantum coherent transport of Dirac fermions in a Bi2Se3 nanowire, revealing long phase coherence lengths and an unusual 1/T temperature dependence indicative of quasi-ballistic behavior.

Contribution

It provides experimental evidence of quasi-ballistic Dirac fermion transport in topological insulator nanowires with a novel temperature dependence of phase coherence.

Findings

Long phase-coherence length of surface states

Observation of multiple harmonics in Aharonov-Bohm oscillations

Unusual 1/T power law for phase coherence length

Abstract

Quantum coherent transport of Dirac fermions in a mesoscopic nanowire of the 3D topological insulator Bi2Se3 is studied in the weak-disorder limit. At very low temperatures, many harmonics are evidenced in the Fourier transform of Aharonov-Bohm oscillations, revealing the long phase-coherence length of surface states. Remarkably, from their exponential temperature dependence, we infer an unusual 1/T power law for the phase coherence length. This decoherence is typical for quasi-ballistic fermions weakly coupled to the dynamics of their environment.