Quantum point contacts (QPC) are fundamental building blocks of nanoelectronic circuits. For their emission dynamics as well as for interaction effects such as the 0.7-anomaly the details of the electrostatic potential are important, but the precise potential shapes are usually unknown. Here, we measure the one-dimensional subband spacings of various QPCs as a function of their conductance and compare our findings with models of lateral parabolic versus hard wall confinement. We find that a gate-defined QPC near pinch-off is compatible with the parabolic saddle point scenario. However, as the number of populated subbands is increased Coulomb screening flattens the potential bottom and a description in terms of a finite hard wall potential becomes more realistic.
@article{arxiv.2002.12303,
title = {Electrostatic potential shape of gate defined quantum point contacts},
author = {Max Geier and Jaan Freudenfeld and Jorge T. Silva and Vladimir Umansky and Dirk Reuter and Andreas D. Wieck and Piet W. Brouwer and Stefan Ludwig},
journal= {arXiv preprint arXiv:2002.12303},
year = {2020}
}
Comments
7+2 pager, 7 figures, v2: published version (minor changes)