Conductance quantization and the 0.7x2e2/h conductance anomaly in one-dimensional hole systems

TL;DR

This study demonstrates ballistic transport and conductance quantization in a high-mobility 1D hole system, revealing a conductance anomaly at 0.7 times the quantum unit, with detailed subband measurements.

Contribution

First observation of the 0.7x2e^2/h conductance anomaly in a 1D hole system with detailed subband spacing analysis.

Findings

Robust conductance quantization observed at millikelvin temperatures.

Subband spacings are smaller than in electron systems but larger than previous hole studies.

First detection of the 0.7 conductance plateau in a 1D hole system.

Abstract

We have studied ballistic transport in a 1D channel formed using surface gate techniques on a back-gated, high-mobility, bilayer 2D hole system. At millikelvin temperatures, robust conductance quantization is observed in the quantum wire formed in the top layer of the bilayer system, without the gate instabilities that have hampered previous studies of 1D hole systems. Using source drain bias spectroscopy, we have measured the 1D subband spacings, which are 5-10 times smaller than in comparable GaAs electron systems, but 2-3 times larger than in previous studies of 1D holes. We also report the first observation of the anomalous conductance plateau at G = 0.7 x 2e2/h in a 1D hole system.