Randomly inhomogeneous Luttinger liquid: Fluctuations of the tunnel conductance

TL;DR

This paper investigates how random variations in electron concentration in a Luttinger liquid cause plasmon localization and fluctuations in tunnel conductance, revealing frequency-dependent localization and bias-related conductance variability.

Contribution

It introduces a model for inhomogeneous Luttinger liquids with random concentration, analyzing plasmon localization and conductance fluctuations, which was not previously addressed.

Findings

Localization length scales as ω^{-2} with frequency

Conductance fluctuations grow as √V with bias voltage

Fluctuation correlation decays as a power law with distance

Abstract

The Luttinger liquid in which the concentration of electrons varies randomly with coordinate is considered. We study the fluctuations of the tunnel conductance, caused by the randomness in the concentration. If the concentration changes slowly on the scale of the Fermi wavelength, its prime role reduces to the scattering of the plasmon waves, propagating along the system. As a result of such a scattering, plasmons get localized. We show that the localization length, $l_{\omega}$, of a plasmon with frequency $\omega$ is inverse proportional to the square of the interaction strength and changes with frequency as $l_{\omega}\propto \omega^{-2}$. If the relative variation of the concentration is small, the randomness--induced correction to the tunnel conductance, $\delta G(V)$, where $V$ is the applied bias, can be expressed through the spectral characteristics of the localized plasmons. The magnitude of the correction, $(\overline{ \delta G^2})^{1/2}/ G$, increases with $V$ as $\sqrt V$. The typical period of the fluctuations in $\delta G(V)$ is of the order of $V$. At a fixed $V$, the correlator of $\delta G$ at different points of the liquid falls off with distance as a power law and oscillates with the period which is one half of the wavelength of a plasmon with frequency $\omega = eV/\hbar$.