Transport properties of a two-dimensional electron liquid at high magnetic field

TL;DR

This paper develops a chiral Luttinger liquid model for the edge states of a 2D electron gas in high magnetic fields, enabling calculation of conductances and tunneling effects in quantum Hall systems, with implications for experimental observations.

Contribution

It derives a general formalism for edge state conductance including tunneling effects, extending previous models without relying on the quantum Hall effect assumption.

Findings

Explicit expressions for conductance corrections due to tunneling.

Demonstration of the formalism with resistance calculations at a quantum point contact.

Identification of a crossover energy affecting the tunneling exponent.

Abstract

The chiral Luttinger liquid model for the edge dynamics of a two-dimensional electron gas in a strong magnetic field is derived from coarse-graining and a lowest Landau level projection procedure at arbitrary filling factors $\nu<1$ -- without reference to the quantum Hall effect. Based on this model, we develop a formalism to calculate the Landauer-B\"uttiker conductances in generic experimental set-ups including multiple leads and voltage probes. In the absence of tunneling between the edges the "ideal" Hall conductances ($G_{ij}= \frac{e^2 \nu}{h}$ if lead $j$ is immediately upstream of lead $i$, and $G_{ij}=0$ otherwise) are recovered. Tunneling of quasiparticles of fractional charge $e^*$ between different edges is then included as an additional term in the Hamiltonian. In the limit of weak tunneling we obtain explicit expressions for the corrections to the ideal conductances. As an illustration of the formalism we compute the current- and temperature-dependent resistance $R_{xx}(I,T)$ of a quantum point contact localized at the center of a gate-induced constriction in a quantum Hall bar. The exponent $\alpha$ in the low-current relation $R_{xx}(I,0) \sim I^{\alpha -2}$ shows a nontrivial dependence on the strength of the inter-edge interaction, and its value changes as $e^*V_H$, where $V_H = \frac{h I}{\nu e^2}$ is the Hall voltage, falls below a characteristic crossover energy $\frac{\hbar c}{d}$, where $c$ is the edge wave velocity and $d$ is the length of the constriction. The consequences of this crossover are discussed vis-a-vis recent experiments in the weak tunneling regime.