Ground state structure and conductivity of quantum wires of infinite length and finite width

TL;DR

This study investigates the ground state structure and conductance of quantum wires of infinite length and finite width, revealing how electron density and polarization affect conductance values, aligning with experimental observations.

Contribution

It provides a detailed analysis of the ground state and conductance behavior of quantum wires using local spin-density approximation, highlighting the role of compressibility ratios.

Findings

At low density, conductance is near 0.7(2e^2/h) and fully polarized.

At higher density, conductance approaches 2e^2/h and the system is paramagnetic.

Conductance depends on the ratio of the system's compressibility to that of free electrons.

Abstract

We have studied the ground state structure of quantum strips within the local spin-density approximation, for a range of electronic densities between $\sim$ 5$\times10^4$ and 2$\times10^6$ cm$^{-1}$ and several strengths of the lateral confining potential. The results have been used to address the conductance $G$ of quantum strips. At low density, when only one subband is occupied, the system is fully polarized and $G$ takes a value which is close to 0.7(2e$^2/h$), decreasing with increasing electron density in agreement with experiments. At higher densities the system becomes paramagnetic and $G$ takes a value near (2e$^2/h$), showing a similar decreasing behaviour with increasing electron density. In both cases, the physical parameter that determines the value of the conductance is the ratio $K/K_0$ of the compressibility of the system over the free one.