Ferromagnetic nematic liquid crystals

This review presents experimental realization and behaviour of the ferromagnetic nematic phase, which is observed in different suspensions of magnetic nanoplatelets. After a general introduction, the challenges in the synthesis of magnetic nanoplatelets and preparation of the nematic suspensions are discussed. A brief explanation of a simple macroscopic theory, which can be used to understand the main features of the ferromagnetic phase, follows. In the main part, four different ferromagnetic nematic systems are presented: (i) ferromagnetic suspensions of the platelets in nematic liquid crystals, (ii) dense suspensions in an isotropic solvent – ferromagnetic ferrofluids, (iii) biaxial ferromagnetic nematic suspensions, and (iv) chiral ferromagnetic suspensions. The main focus is on the formation of the ferromagnetic phases and the growth of the magnetic domains. At the end, dynamics of ferromagnetic liquid crystals and methods for their observation are briefly discussed.

本综述系统阐述了在不同磁性纳米片（magnetic nanoplatelets）悬浮液中观测到的铁磁向列相（ferromagnetic nematic phase）的实验实现方式与行为特性。开篇总论之后，本文将讨论磁性纳米片的合成难点与向列相悬浮液的制备工艺。随后将简要介绍可用于阐释铁磁向列相核心特征的简易宏观理论。正文部分将介绍四类不同的铁磁向列体系：(i) 向列液晶中的片晶铁磁悬浮体系；(ii) 各向同性溶剂中的致密悬浮体系——铁磁磁流体；(iii) 双轴铁磁向列悬浮体系；(iv) 手性铁磁悬浮体系。本文核心聚焦于铁磁相的形成过程与磁畴的生长演化。文末将简要探讨铁磁液晶的动力学特性及其观测方法。