Conductance and density of states anomalies as resonances of energy bands in disordered coupled chains

TL;DR

This paper investigates how off-diagonal disorder in coupled chains causes anomalies in density of states and conductance, linked to band resonances, and extends understanding beyond the zero-energy case with analytical predictions verified numerically.

Contribution

It reveals that conductance and density of states anomalies arise from band resonances in disordered chains, not only at zero energy, and provides series expansions for these effects.

Findings

Anomalies occur at energies other than zero due to band resonances.

Even-odd chain number effects are explained by the same resonances.

Series expansions accurately predict resonant contributions to conductance.

Abstract

We show that off-diagonal nearest neighbor disorder in quasi-one-dimensional single particle tight-binding coupled chains leads to anomalies in the density of states and in the mean conductance, that can be interpreted as due to specific resonances of the band structure of the perfect system underlying the disordered one. We demonstrate that this phenomenology may appear not necessarily at the energy E=0 as reported so far in the literature and we show that also the even-odd chain number effect on the mean conductance is ruled by the same resonances. For different cases we provide a series expansion for the resonant contribution to the mean conductance. These expansions allow to make predictions well verified numerically.