Structure factor of model bidisperse ferrofluids with relatively weak interparticle interactions.

Area of Science:

• Statistical Mechanics
• Soft Matter Physics
• Magnetohydrodynamics

Background:

• Understanding the thermodynamics of magnetic fluids is crucial for applications.
• Polydispersity in magnetic fluids significantly impacts their structural and thermodynamic properties.
• Accurate theoretical models are needed to complement experimental and simulation data.

Purpose of the Study:

• To develop a theoretical framework for the pair correlation function of bidisperse magnetic dipolar hard- and soft-spheres.
• To investigate the influence of steric potential and dipolar strength on the structure factor.
• To validate theoretical predictions against molecular dynamics simulations and assess the range of applicability.

Main Methods:

• Development of a theoretical approach using diagram technique.
• Calculation of the virial expansion for the pair correlation function.
• Comparison with molecular dynamics simulation data.

Main Results:

• The isotropic centre-centre structure factor is largely independent of the short-range repulsion type.
• The theoretical model's validity range concerning density and dipolar strength was determined through simulation comparisons.
• Influence of granulometric composition on the structure factor's first peak was analyzed.

Conclusions:

• The developed theoretical approach provides insights into the structure of bidisperse magnetic fluids.
• The structure factor's robustness to steric interactions simplifies analysis for magnetic fluid systems.
• Potential for extracting structural information from scattering experiments like small-angle neutron scattering was explored.