One-dimensional weak antilocalization and band Berry phases in HgTe wires

TL;DR

This study investigates weak antilocalization effects in narrow HgTe wires, revealing how band topology influences quantum interference and Berry phases, with implications for topological materials.

Contribution

It demonstrates the persistence of WAL in HgTe wires regardless of Rashba splitting and links WAL behavior to Dirac-like band topology and Berry phases.

Findings

WAL persists even when Rashba splitting is near zero.

WAL signal is weaker in normal band ordering compared to inverted.

Extracted Berry phases exceed  for gapless Dirac fermions.

Abstract

We study the weak antilocalization (WAL) effect in the magnetoresistance of narrow HgTe wires fabricated in quantum wells (QWs) with normal and inverted band ordering. Measurements at different gate voltages indicate that the WAL is only weakly affected by Rashba spin-orbit splitting and persists when the Rashba splitting is about zero. The WAL signal in wires with normal band ordering is an order of magnitude smaller than for inverted ones. These observations are attributed to a Dirac-like topology of the energy bands in HgTe QWs. From the magnetic-field and temperature dependencies we extract the dephasing lengths and band Berry phases. The weaker WAL for samples with a normal band structure can be explained by a non-universal Berry phase which always exceeds \pi, the characteristic value for gapless Dirac fermions.