Tuning electronic and phononic states with hidden order in disordered crystals

TL;DR

This paper demonstrates how hidden local correlations in disordered crystals can significantly alter electronic and phononic properties, enabling property tuning without traditional symmetry breaking.

Contribution

It reveals how hidden order in disordered crystals affects electronic and phononic band structures, offering a new approach to material property control.

Findings

Hidden order can open band gaps in electronic structures.

Local correlations influence phononic mode localization.

Control over hidden order enables tuning of material properties.

Abstract

Disorder in crystals is rarely random, and instead involves local correlations whose presence and nature are hidden from conventional crystallographic probes. This hidden order can sometimes be controlled, but its importance for physical properties of materials is not well understood. Using simple models for electronic and interatomic interactions, we show how crystals with identical average structures but different types of hidden order can have very different electronic and phononic band structures. Increasing the strength of local correlations within hidden-order states can open band gaps and tune mode (de)localisation -- both mechanisms allowing for fundamental changes in physical properties without long-range symmetry breaking. Taken together, our results demonstrate how control over hidden order offers a new mechanism for tuning material properties, orthogonal to the conventional principles of (ordered) structure/property relationships.