Ferromagnetic Switching of Knotted Vector Fields in Liquid Crystal Colloids.
Ferromagnetic Switching of Knotted Vector Fields in Liquid Crystal Colloids.
复制标题
液晶胶体中打结矢量场的铁磁切换。
DOI：
10.1103/physrevlett.115.097802
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发表时间：
2015
影响因子：
8.6
通讯作者：
I. Smalyukh
中科院分区：
文献类型：
--
作者：
Qiaoxuan Zhang;Paul J. Ackerman;Qingkun Liu;I. Smalyukh
我们实验上实现了多畴和单畴手性铁磁液晶胶体，表现出孤立和打结的矢量场配置。这些胶体铁磁体由手性液晶中铁磁纳米片的分散体形成，表现出单个片的磁偶极矩的自发长程对准，从而产生连续的磁化场M（r）。表面限制和手征性的竞争效应促使自发形成，并使光学产生的局域扭曲孤子结构的双扭曲管和环面结的M（r），表现出很强的灵敏度弱磁场的方向小于1 mT。数值模拟，通过自由能最小化，以达到一个依赖于场的三维M（r），显示出良好的协议与实验，并提供了观察到的场配置和相应的物理基础的环面结拓扑结构的见解。
We experimentally realize polydomain and monodomain chiral ferromagnetic liquid crystal colloids that exhibit solitonic and knotted vector field configurations. Formed by dispersions of ferromagnetic nanoplatelets in chiral nematic liquid crystals, these colloidal ferromagnets exhibit spontaneous long-range alignment of magnetic dipole moments of individual platelets, giving rise to a continuum of the magnetization field M(r). Competing effects of surface confinement and chirality prompt spontaneous formation and enable the optical generation of localized twisted solitonic structures with double-twist tubes and torus knots of M(r), which exhibit a strong sensitivity to the direction of weak magnetic fields ∼1 mT. Numerical modeling, implemented through free energy minimization to arrive at a field-dependent three-dimensional M(r), shows a good agreement with experiments and provides insights into the torus knot topology of observed field configurations and the corresponding physical underpinnings.