de Gennes Narrowing and the Relationship Between Structure and Dynamics in Self-Organized Ion Beam Nanopatterning

TL;DR

This paper explores the relationship between structure and dynamics in self-organized ion beam nanopatterning of silicon, revealing a de Gennes-like narrowing phenomenon with complex relaxation behaviors linked to ripple pattern persistence.

Contribution

It uncovers a novel de Gennes narrowing-like relationship in ion beam nanopatterning and characterizes the complex relaxation dynamics of surface ripples.

Findings

Discovery of de Gennes narrowing during nanopatterning

Observation of compressed exponential relaxation at ripple scales

Simulation reproduces observed dynamic behaviors

Abstract

Investigating the relationship between structure and dynamical processes is a central goal in condensed matter physics. Perhaps the most noted relationship between the two is the phenomenon of de Gennes narrowing, in which relaxation times in liquids are proportional to the scattering structure factor. Here a similar relationship is discovered during the self-organized ion beam nanopatterning of silicon using coherent x-ray scattering. However, in contrast to the exponential relaxation of fluctuations in classic de Gennes narrowing, the dynamic surface exhibits a wide range of behaviors as a function of length scale, with a compressed exponential relaxation at lengths corresponding to the dominant structural motif - self-organized nanoscale ripples. These behaviors are reproduced in simulations of a nonlinear model describing the surface evolution. We suggest that the compressed exponential behavior observed here is due to the morphological persistence of the self-organized surface ripple patterns which form and evolve during ion beam nanopatterning.