Gradient and Amplitude Scattering in Surface-Corrugated Waveguides

TL;DR

This paper reveals that in multi-mode waveguides, square-gradient surface roughness significantly dominates scattering effects when the surface disorder correlation length is small, a factor overlooked in previous research.

Contribution

It demonstrates the dominance of square-gradient scattering in waveguides with small correlation length, highlighting an overlooked aspect in surface scattering studies.

Findings

Square-gradient terms dominate scattering for small correlation lengths.

Existing models underestimate scattering effects by neglecting square-gradient contributions.

Surface roughness impact is significant even at small roughness heights.

Abstract

We investigate the interplay between amplitude and square-gradient scattering from the rough surfaces in multi-mode waveguides (conducting quantum wires). The main result is that for any (even small in height) roughness the square-gradient terms in the expression for the wave scattering length (electron mean free path) are dominant, provided the correlation length of the surface disorder is small enough. This important effect is missed in existing studies of the surface scattering.