Landau Description of Ferrofluid to Ferronematic Phase Transition
Landau Description of Ferrofluid to Ferronematic Phase Transition
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铁磁流体到铁电相变的兰道描述
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
H. Brand
中科院分区：
文献类型：
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作者：
H. Pleiner;E. Jarkova;H. Müller;H. Brand
提出了一种Landau型自由能函数，用来描述从各向同性（超顺磁性）铁磁流体直接或通过超顺磁性铁磁液晶转变为铁磁液晶的相变.这两个向列相通常都被称为“铁磁性”，尽管它们是不同的相。两者都表现出有序，但只有铁磁相表现出自发磁有序。磁有序与磁有序的相互作用特别有趣。在本模型中，具有铁磁有序但没有铁磁有序的相是不可能的，因为前者总是意味着后者（但反之亦然）。在强外部磁场的存在下，这些转变被模糊，并且不同的铁磁相变得彼此更加相似。
A Landau-type free energy function is presented to describe the phase transitions from an isotropic (superparamagnetic) ferrofluid to a ferromagnetic nematic liquid crystal either directly or via a superparamagnetic nematic liquid crystal. These two nematic phases are usually both called ’ferronematic’, although they are distinct phases. Both show nematic ordering, but only the ferromagnetic phase shows spontaneous magnetic ordering, additionally. The interplay of nematic with magnetic order is of special interest. A phase with ferromagnetic order but no nematic order is not possible in the present model, since the former always implies the latter (but not vice versa). In the presence of a strong external magnetic field these transitions are smeared out and the different ferronematic phases become more similar to each other.