Critical Casimir Interactions Between Spherical Particles in the Presence of the Bulk Ordering Fields

TL;DR

This paper investigates critical Casimir forces between spherical particles in a critical binary mixture, introducing a Monte Carlo simulation method to compute interaction potentials and analyzing how bulk fields influence these forces near the phase transition.

Contribution

It presents a novel Monte Carlo simulation approach for calculating critical Casimir interactions between spherical particles in the Ising universality class.

Findings

Strongest interactions occur below the critical point.

Interaction strength depends on the component concentration in the mixture.

Numerical method effectively captures the influence of bulk fields on forces.

Abstract

The spatial suppression of order parameter fluctuations in a critical media produces Critical Casimir forces acting on confining surfaces. This scenario is realized in a critical binary mixture near the demixing transition point that corresponds to the second order phase transition of the Ising universality class. Due to these critical interactions similar colloids, immersed in a critical binary mixture near the consolute point, exhibit attraction. The numerical method for computation of the interaction potential between two spherical particles using Monte Carlo simulations for the Ising model is proposed. This method is based on the integration of the local magnetization over the applied local magnetic field. For the stronger interaction the concentration of the component of the mixture that does not wet colloidal particles, should be larger, than the critical concentration. The strongest amplitude of the interactions is observed below the critical point.