Inhomogeneous ground state and the coexistence of two length scales near phase transitions in real solids

TL;DR

This paper demonstrates that dislocations in real crystals cause inhomogeneous ground states, transforming phase transitions into percolative phenomena and explaining the observed two length scales in scattering experiments.

Contribution

It reveals how dislocation-induced disorder alters critical behavior, leading to inhomogeneous ground states and a new understanding of phase transition phenomena in solids.

Findings

Dislocations cause inhomogeneous ground states in crystals.

Phase transitions become percolative due to disorder.

Two length scales observed in experiments are explained by this model.

Abstract

Real crystals almost unavoidably contain a finite density of dislocations. We show that this generic type of long--range correlated disorder leads to a breakdown of the conventional scenario of critical behavior and standard renormalization group techniques based on the existence of a simple, homogeneous ground state. This breakdown is due to the appearance of an inhomogeneous ground state that changes the character of the phase transition to that of a percolative phenomenon. This scenario leads to a natural explanation for the appearance of two length scales in recent high resolution small-angle scattering experiments near magnetic and structural phase transitions.