Disorder suppression and precise conductance quantization in constrictions of PbTe quantum wells

TL;DR

This study demonstrates that PbTe quantum well constrictions exhibit precise conductance quantization despite charged defects, due to PbTe's paraelectric properties that suppress Coulomb potential tails, unlike other systems.

Contribution

It reveals that PbTe's paraelectric nature enables exact conductance quantization even with charged defects, a novel finding in quantum transport.

Findings

Achieved quantized conductance in PbTe constrictions despite defects

Attributed suppression of Coulomb tails to PbTe's high dielectric constant

Demonstrated similarity to AlGaAs/GaAs quantum structures

Abstract

Conductance quantization was measured in submicron constrictions of PbTe, patterned into narrow,12 nm wide quantum wells deposited between Pb$_{0.92}$Eu$_{0.08}$Te barriers. Because the quantum confinement imposed by the barriers is much stronger than the lateral one, the one-dimensional electron energy level structure is very similar to that usually met in constrictions of AlGaAs/GaAs heterostructures. However, in contrast to any other system studied so far, we observe precise conductance quantization in $2e^2/h$ units, {\it despite of significant amount of charged defects in the vicinity of the constriction}. We show that such extraordinary results is a consequence of the paraelectric properties of PbTe, namely, the suppression of long-range tails of the Coulomb potentials due to the huge dielectric constant.