Condensation, demixing, and orientational ordering of magnetic colloidal suspensions.
Condensation, demixing, and orientational ordering of magnetic colloidal suspensions.
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磁胶体悬浮液的缩合、分层和定向排序
DOI：
10.1103/physreve.91.052127
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
M. Schoen
中科院分区：
文献类型：
--
作者：
S. M. Cattes;S. H. L. Klapp;M. Schoen
在这项工作中，我们研究了悬浮在简单非磁性溶剂中的磁性粒子的相行为。磁性粒子被建模为携带三维经典海森堡自旋的球形粒子，而溶剂分子被视为球对称的Lennard-Jones粒子。在经典密度泛函理论(DFT)框架下研究了磁性粒子和溶剂的二元混合物。在DFT中，对关联是在修正的平均场水平上处理的，在该水平上它们由取向相关的梅耶尔函数来近似。在没有外加磁场的情况下，根据磁性粒子的浓度，观察到四种一般类型的相图。在这种情况下，我们观察到取向有序(极化)和无序相之间的液-液共存，其特征是磁性粒子的浓度略有不同。液-液共存受到外场的抑制，当外场强度足够大时，液-液共存完全消失。
In this work we study the phase behavior of magnetic particles suspended in a simple nonmagnetic solvent. Magnetic particles are modelled as spherical particles carrying a three-dimensional, classical Heisenberg spin, whereas solvent molecules are treated as spherically symmetric Lennard-Jones particles. The binary mixture of magnetic particles and solvent is studied within the framework of classical density functional theory (DFT). Within DFT pair correlations are treated at the modified mean-field level at which they are approximated by orientation dependent Mayerfunctions. In the absence of an external magnetic field four generic types of phase diagrams are observed depending on the concentration of magnetic particles. In this case we observe liquid-liquid phase coexistence between an orientationally ordered (polarized) and a disordered phase characterized by slightly different concentrations of magnetic particles. Liquid-liquid phase coexistence is suppressed by an external field and vanishes completely if the strength of the field is sufficiently large.