Collective excitations in active solids featuring alignment interactions

TL;DR

This paper investigates the fluctuation spectra of active solids with alignment interactions, revealing collectively excitable modes and their relation to entropy production, thus advancing understanding of nonequilibrium active matter.

Contribution

It provides a theoretical analysis of excitability and fluctuation spectra in active solids with alignment interactions, highlighting differences from passive solids and linking excitations to entropy production.

Findings

Existence of collectively excitable modes in active migrating solids

Differences in fluctuation spectra compared to passive solids

Relation between excitation modes and entropy production

Abstract

With increasing emphasis on the study of active solids, the features of these classes of nonequilibrium systems and materials beyond their mere existence shift into focus. One concept of active solids addresses them as active, self-propelled units that are elastically linked to each other. The emergence of orientationally ordered, collectively moving states in such systems has been demonstrated. We here analyze the excitability of such collectively moving elastic states. To this end, we determine corresponding fluctuation spectra. They indicate that collectively excitable modes exist in the migrating solid. Differences arise when compared to those of corresponding passive solids. We provide evidence that the modes of excitation associated with the intrinsic fluctuations are related to corresponding modes of entropy production. Overall, we hope to stimulate by our investigation future experimental studies that focus on excitations in active solids.