Phase transitions in ensembles of solitons induced by an optical pumping or a strong electric field

TL;DR

This paper investigates phase transitions in soliton ensembles triggered by optical or electric stimuli, revealing confinement and aggregation phenomena through advanced numerical modeling including Coulomb interactions.

Contribution

It introduces a specialized Monte Carlo algorithm for simulating soliton ensembles in 2D and 3D, accounting for long-range forces and Coulomb interactions, advancing understanding of phase transitions.

Findings

Confirmation of the confinement transition in soliton ensembles

Observation of pattern formation during aggregation transition

Effect of Coulomb repulsion on phase transition behavior

Abstract

The latest trend in studies of modern electronically and/or optically active materials is to provoke phase transformations induced by high electric fields or by short (femtosecond) powerful optical pulses. The systems of choice are cooperative electronic states whose broken symmetries give rise to topological defects. For typical quasi-one-dimensional architectures, those are the microscopic solitons taking from electrons the major roles as carriers of charge or spin. Because of the long-range ordering, the solitons experience unusual super-long-range forces leading to a sequence of phase transitions in their ensembles: the higher-temperature transition of the confinement and the lower one of aggregation into macroscopic walls. Here we present results of an extensive numerical modeling for ensembles of both neutral and charged solitons in both two- and three-dimensional systems. We suggest a specific Monte Carlo algorithm preserving the number of solitons, which substantially facilitates the calculations, allows to extend them to the three-dimensional case and to include the important long-range Coulomb interactions. The results confirm the first confinement transition, except for a very strong Coulomb repulsion, and demonstrate a pattern formation at the second transition of aggregation.