Topological Defects in Amorphous Solids

TL;DR

This paper reviews how topological defect concepts, traditionally used in crystalline materials, are being adapted to understand the mechanical properties and dynamics of amorphous solids like glasses.

Contribution

It synthesizes recent theoretical, numerical, and experimental advances demonstrating the relevance of topological ideas in disordered materials.

Findings

Topological defect observables are identifiable in amorphous solids.

Topological concepts can provide a first-principles framework for amorphous material behavior.

Recent studies link topological defects to mechanical response in glasses.

Abstract

Topological defects (TDs) are crucial for understanding important physical properties of crystalline materials including mechanical failure, ion transport, and two-dimensional melting. This concept has not translated to disordered materials like glasses because these solids have no obvious reference structure that can be used to define TDs. As a result, key properties related to those listed above have typically been modeled using purely phenomenological approaches. Recent studies have demonstrated that certain observables commonly associated with TDs can also be identified in disordered solids indicating that topological concepts may be as crucial in amorphous solids as in crystals. This hints that TDs may offer a first-principles framework for understanding their mechanical response and complex spatiotemporal dynamics. In this Perspective, we review recent theoretical, numerical, and experimental studies that have exploited topological concepts to rationalize mechanical properties of amorphous solids. We also highlight pressing open questions and some promising directions for future research in the field.