Scattering and transport properties of tight-binding random networks

TL;DR

This paper investigates how the scattering and transport properties of tight-binding random networks transition from insulating to metallic states as the network connectivity varies, revealing universal relations dependent on a combined parameter.

Contribution

It introduces a numerical analysis of scattering and transport in tight-binding networks, identifying a universal parameter and relations governing the transition from insulator to metal.

Findings

Smooth crossover from insulating to metallic behavior observed

Invariant quantities for fixed =N across different network sizes

Proposed universal relation between scattering, conductance, and disorder parameter

Abstract

We study numerically scattering and transport statistical properties of tight-binding random networks characterized by the number of nodes $N$ and the average connectivity $\alpha$. We use a scattering approach to electronic transport and concentrate on the case of a small number of single-channel attached leads. We observe a smooth crossover from insulating to metallic behavior in the average scattering matrix elements $\bra |S_{mn}|^2 \ket$, the conductance probability distribution $w(T)$, the average conductance $\bra T \ket$, the shot noise power $P$, and the elastic enhancement factor $F$ by varying $\alpha$ from small ($\alpha \to 0$) to large ($\alpha \to 1$) values. We also show that all these quantities are invariant for fixed $\xi=\alpha N$. Moreover, we proposes a heuristic and universal relation between $\bra |S_{mn}|^2 \ket$, $\bra T \ket$, and $P$ and the disorder parameter $\xi$.