Phase separation dynamics in a two-dimensional magnetic mixture

TL;DR

This paper uses density functional theory to study phase separation in a two-dimensional magnetic mixture, revealing demixing driven by magnetic interactions and analyzing the interface and dynamics of separation.

Contribution

It introduces a microscopic DFT and DDFT approach to analyze phase separation and interface properties in a 2D magnetic mixture with Gaussian soft spheres.

Findings

Demixing phase transition occurs at high magnetic coupling and density.

Phase diagrams in density-concentration plane are calculated.

Dynamical analysis includes nucleation and spinodal decomposition.

Abstract

Based on classical density functional theory (DFT), we investigate the demixing phase transition of a two-dimensional, binary Heisenberg fluid mixture. The particles in the mixture are modeled as Gaussian soft spheres, where one component is characterized by an additional classical spin-spin interaction of Heisenberg type. Within the DFT we treat the particle interactions using a mean-field approximation. For certain magnetic coupling strengths we calculate phase diagrams in the density-concentration plane. For sufficiently large coupling strengths and densities, we find a demixing phase transition driven by the ferromagnetic interactions of the magnetic species. We also provide a microscopic description (i.e., density profiles) of the resulting non-magnetic/magnetic fluid-fluid interface. Finally, we investigate the phase separation using dynamical density functional theory (DDFT), considering both nucleation processes and spinodal demixing.