Correlation effects in quasi one dimensional electron wires

TL;DR

This study uses quantum Monte Carlo simulations to investigate how electron correlations influence phase transitions, spin behavior, and localization in quasi-one-dimensional electron wires with varying interaction ranges and densities.

Contribution

It provides a detailed analysis of correlation effects, including the liquid to quasi Wigner crystal transition and spinless fermion behavior, incorporating realistic screening and finite system size effects.

Findings

Observation of liquid to quasi Wigner crystal crossover at low densities.

Identification of spinless fermion behavior at very low electron concentrations.

Agreement of simulated charge and spin velocities with experimental data near localization transition.

Abstract

We explore the role of electron correlation in quasi one dimensional quantum wires as the range of the interaction potential is changed and their thickness is varied by performing exact quantum Monte Carlo simulations at various electronic densities. In the case of unscreened interactions with a long range 1/x tail there is a crossover from a liquid to a quasi Wigner crystal state as the density decreases. When this interaction is screened, quasi long range order is prevented from forming, although a significant correlation with 4 k_F periodicity is still present at low densities. At even lower electron concentration, exchange is suppressed and the spin-dependent interactions become negligible, making the electrons behave like spinless fermions. We show that this behavior is shared by the long range and screened interactions by studying the spin and charge excitations of the system in both cases. Finally, we study the effect of electron correlations in the double quantum wire experiment [Steinberg et al., Phys. Rev. B 77, 113307 (2006)], by introducing an accurate model for the screening in the experiment and explicitly including the finite length of the system in our simulations. We find that decreasing the electron density drives the system from a liquid to a state with quite strong 4 k_F correlations. This crossover takes place around $20 \mu m^{-1}$, the density where the electron localization occurs in the experiment. The charge and spin velocities are also in remarkable agreement with the experimental findings in the proximity of the crossover. We argue that correlation effects play an important role at the onset of the localization transition.