Dislocations and crystallization dynamics of chiral soliton lattices

TL;DR

This paper develops a new theoretical model to simulate the dynamic formation of dislocations in chiral soliton lattices, revealing spontaneous dislocation creation and complex helical structures influenced by external fields.

Contribution

It introduces a modified topological term in the field theory to enable the study of dislocation dynamics in CSLs, bridging high-energy physics and materials science.

Findings

Dislocations spontaneously form in 2D and 3D CSLs.

Helical screw dislocations resemble DNA structures.

External fields influence CSL density and formation speed.

Abstract

Dislocations, as topological defects in crystal lattices, are fundamental to understanding plasticity in materials. Similar periodic structures also arise in continuum field theories, such as chiral soliton lattices (CSLs), which appear in condensed matter systems like chiral magnets and in high-energy contexts such as quantum chromodynamics in strong magnetic field or under rapid rotation. This work investigates whether dislocations can dynamically form within such emergent CSLs. The chiral sine-Gordon model, reduced from the aforementioned examples by certain truncations, is useful to determine the ground state but it cannot describe time evolution, lacks dynamical formation or leads to singular dislocations, because its equations of motion do not contain a topological term. We propose a field-theoretical model including the topological term coupled to external fields resolving these issues by modifying the topological term so it affects the dynamics. Using numerical simulations, we study the real-time formation of CSLs in two and three spatial dimensions. In 2D, edge dislocations emerge spontaneously, guiding soliton growth and later annihilating to leave a stable CSL. In 3D, both edge and screw dislocations form; the latter exhibits helical structure influenced by the external field. We find stable double helical screw dislocations looking like a double helix staircase or DNA. We then demonstrate the formation of helical dislocations and analyze how the external field strength affects CSL density and formation speed. Our results provide a novel theoretical framework for understanding dislocations in solitonic structures, connecting high-energy field theory with materials science phenomena.