Ballistic, diffusive, and localized transport in surface-disordered systems: Two-mode waveguide

TL;DR

This paper analytically explores how surface roughness symmetry in two-mode waveguides influences various transport regimes, revealing the significant impact of square-gradient scattering on transmission properties.

Contribution

It provides a detailed analytical analysis of transport regimes in two-mode surface-disordered waveguides, highlighting the role of surface symmetry and square-gradient scattering.

Findings

Symmetric roughness enables ballistic, localized, and coexistence regimes.

Antisymmetric roughness can induce a diffusive transport regime.

Square-gradient scattering significantly affects transmission, often neglected in previous studies.

Abstract

This paper presents an analytical study of the coexistence of different transport regimes in quasi-one-dimensional surface-disordered waveguides (or electron conductors). To elucidate main features of surface scattering, the case of two open modes (channels) is considered in great detail. Main attention is paid to the transmission in dependence on various parameters of the model with two types of rough-surface profiles (symmetric and antisymmetric). It is shown that depending on the symmetry, basic mechanisms of scattering can be either enhanced or suppressed. As a consequence, different transport regimes can be realized. Specifically, in the waveguide with symmetric rough boundaries, there are ballistic, localized and coexistence transport regimes. In the waveguide with antisymmetric roughness of lateral walls, another regime of the diffusive transport can arise. Our study allows to reveal the role of the so-called square-gradient scattering which is typically neglected in literature, however, can give a strong impact to the transmission.