Nonlinear hopping transport in ring systems and open channels

TL;DR

This paper analyzes nonlinear hopping transport in one-dimensional ring and open channel systems, deriving analytical results and exploring effects of disorder, frequency, and system size on transport behavior and rectification.

Contribution

It provides analytical insights into nonlinear hopping transport in ordered and disordered systems, highlighting differences between ring and open channel geometries.

Findings

Anomalously large effective jump lengths can occur in ordered systems.

Rectification effects depend on disorder type and system size.

Ring models approximate open channel behavior at high frequencies.

Abstract

We study the nonlinear hopping transport in one-dimensional rings and open channels. Analytical results are derived for the stationary current response to a constant bias without assuming any specific coupling to the external fields. It is shown that anomalous large effective jump lengths, as observed in recent experiments by taking the ratio of the third order nonlinear and the linear conductivity, can occur already in ordered systems. Rectification effects due to site energy disorder in ring systems are expected to become irrelevant for large system sizes. In open channels in contrast, rectification effects occur already for disorder in the jump barriers and do not vanish in the thermodynamic limit. Numerical solutions for a sinusoidal bias show that the ring system provides a good description for the transport behavior in the open channel for intermediate and high frequencies. For low frequencies temporal variations in the mean particle number have to be taken into account in the open channel, which cannot be captured in the more simple ring model.