Persistence of two-dimensional topological insulator state in wide HgTe quantum well

TL;DR

This study experimentally confirms that wide HgTe quantum wells maintain a two-dimensional topological insulator state, with edge state transport observed at low temperatures and in small samples, extending previous findings for narrower wells.

Contribution

It demonstrates the persistence of the topological insulator state in wider HgTe quantum wells, supported by resistance measurements and edge state transport analysis.

Findings

Edge state transport observed in 1 mm wide samples below 1 K

Quasiballistic edge transport in samples smaller than 10 μm

Insulating gap of a few meV inferred from temperature dependence

Abstract

Our experimental studies of electron transport in wide (14 nm) HgTe quantum wells confirm persistence of a two-dimensional topological insulator state reported previously for narrower wells, where it was justified theoretically. Comparison of local and nonlocal resistance measurements indicate edge state transport in the samples of about 1 mm size at temperatures below 1 K. Temperature dependence of the resistances suggests an insulating gap of the order of a few meV. In samples with sizes smaller than 10 $\mu$m a quasiballistic transport via the edge states is observed.