Abstract
We investigate experimentally transport in gated microsctructures containing a band-inverted HgTe/HgCdTe quantum well. Measurements of nonlocal resistances using many contacts prove that in the depletion regime the current is carried by the edge channels, as expected for a two-dimensional topological insulator. However, high and nonquantized values of channel resistances show that the topological protection length (i.e., the distance on which the carriers in helical edge channels propagate without backscattering) is much shorter than the channel length, which is 100 m. The weak temperature dependence of the resistance and the presence of temperature dependent reproducible quasiperiodic resistance fluctuations can be qualitatively explained by the presence of charge puddles in the well, to which the electrons from the edge channels are tunnel-coupled.
- Received 24 July 2013
DOI:https://doi.org/10.1103/PhysRevB.88.165309
©2013 American Physical Society