Ferrofluid nucleus phase transitions in an external uniform magnetic field

TL;DR

This study uses molecular dynamics simulations to analyze phase transitions in ferrofluids under external magnetic fields, revealing discrepancies with some theoretical models but aligning well with certain experimental conditions.

Contribution

It provides a detailed simulation-based analysis of ferrofluid phase transitions, highlighting differences from existing theories and better matching specific experimental scenarios.

Findings

Simulated phase diagram matches experimental data for certain parameters.

The phase coexistence curve trend opposes some theoretical predictions.

Results better describe the transition from linear chains to dense globes.

Abstract

The phase transition between a massive dense phase and a diluted superparamagnetic phase has been studied by means of a direct molecular dynamics simulation. The equilibrium structures of the ferrofluid aggregate nucleus are obtained for different values of a temperature and an external magnetic field magnitude. An approximate match of experiment and simulation has been shown for the ferrofluid phase diagram coordinates "field-temperature". The provided phase coexistence curve has an opposite trend comparing to some of known theoretical results. This contradiction has been discussed. For given experimental parameters, it has been concluded that the present results describe more precisely the transition from linear chains to a dense globes phase. The theoretical concepts which provide the opposite binodal curve dependency trend match other experimental conditions: a diluted ferrofluid, a high particle coating rate, a high temperature, and/or a less particles coupling constant value.