Department of Electrical and Computer Engineering, Ben Gurion University of the Negev, Beer Sheva, Israel.
J Phys Condens Matter. 2010 Dec 8;22(48):486005. doi: 10.1088/0953-8984/22/48/486005. Epub 2010 Nov 16.
Small ferrite-disk particles with magnetostatic (magneto-dipole) oscillations are characterized by the topological-phase states-the vortex states. In a recently published paper (Kamenetskii et al 2010 Phys. Rev. A 81 053823), it was shown that such magnetic vortices act as traps, providing purely subwavelength confinement of electromagnetic fields. The symmetry properties of magnetostatic-vortex ferrite disks allow one to propose new-type subwavelength microwave structures. In this paper it is demonstrated that the unique topological properties of the fields in a ferrite disk are intimately related to the symmetry breaking effects of magnetostatic oscillations. This analysis is based on postulates about a physical meaning of the magnetostatic-potential function ψ(r, t) as a complex scalar wavefunction, which presumes a long-range phase coherence in magnetic dipole-dipole interactions. The proper solutions are found based on an analysis of magnetostatic-wave propagation in a helical coordinate system. It is shown that while a composition of two helical waves may acquire a geometrical phase over-running of 2π during a period, every separate helical wave has a dynamical phase over-running of π and so behaves as a double-valued function. This results in the appearance of helical-mode magnetostatic resonances in quasi-2D ferrite disks. The solutions give magnetostatic-wave power-flow-density vortices with cores at the disk center and azimuthally running waves of magnetization. The near fields of magnetostatic-vortex ferrite-disk particles are characterized by space-time symmetry violation. For incident electromagnetic waves, such particles, with sizes much less than the free-space electromagnetic wavelength, appear as local singular regions. From the properties of a composition of magnetostatic-vortex ferrite-disk particles, one may propose novel metamaterials-singular metamaterials.
具有静磁（磁偶极）振荡的小铁氧体圆盘颗粒的特征在于拓扑相态——涡旋态。在最近发表的一篇论文（Kamenetskii 等人，2010 年，物理评论 A81，053823）中，表明这种磁性涡旋充当陷阱，提供纯粹亚波长的电磁场限制。静磁涡旋铁氧体圆盘的对称性质允许提出新型亚波长微波结构。在本文中，证明了铁氧体盘中的磁场的独特拓扑性质与静磁振荡的对称破缺效应密切相关。这种分析基于假设静磁势函数 ψ(r, t)作为复标量波函数的物理意义的前提，假定磁偶极子-偶极子相互作用中的长程相位相干性。基于在螺旋坐标系中传播的静磁场波的分析，找到了适当的解。结果表明，虽然两个螺旋波的组合可能在一个周期内获得 2π 的几何相位超量，但每个单独的螺旋波具有 π 的动态相位超量，因此表现为双值函数。这导致在准二维铁氧体盘中出现螺旋模式静磁共振。解给出了静磁场波功率流密度涡旋，其核心位于磁盘中心并且沿方位运行的磁化波。静磁涡旋铁氧体圆盘颗粒的近场具有时空对称破坏的特征。对于入射电磁波，尺寸远小于自由空间电磁波波长的这些颗粒表现为局部奇异区域。从静磁涡旋铁氧体圆盘颗粒的组合性质，可以提出新型超材料——奇异超材料。
