3D transport of spin waves in curved nano-membranes

铁磁体中的自旋波（或磁振子）可以在不涉及任何电荷输运的情况下传播介观距离，为绿色数据处理铺平了道路。因此，利用电子的自旋自由度来代替其电荷进行数据处理是一个巨大的挑战。事实上，在过去的十年中，人们对自旋波的激发、输运和操纵以及探测进行了大量的研究，这些研究主要集中在铁磁薄膜中。然而，材料科学的最新进展允许生产卷曲和柔性的三维弯曲磁性纳米膜，如纳米管，球形帽。理论工作预测，当曲率半径达到本征长度尺度时，如畴壁宽度或磁振子波长，可能会出现令人惊讶的效应。在简单铁磁体中，曲率诱导的磁手性效应可以导致手性畴壁的形成，使磁性织构稳定为Skyrmions，或者导致非互易自旋波传播。该项目试图合并自旋波输运和磁手性效应的交换和经典的偶极-偶极起源。目的是对微磁性框架内三维弯曲结构中曲率和拓扑结构对自旋波输运的影响有一个基本的认识。曲线系统中的磁手性效应源于对称交换和/或偶极-偶极相互作用，为自旋波的输运和操纵带来了进一步的自由度。此外，曲线系统提供了在第三几何维度探索自旋波输运的可能性。方案中考虑的各种几何形状——从圆形到六边形纳米管和圆形纳米线的过渡以及波纹结构，以及所有与先前研究的磁性纳米管相连的结构——有望带来长远的影响，有助于扩展自旋波控制的物理工具箱，并进一步促进三维纳米膜在磁畴学领域的发展。

Spin waves (or magnons) in ferromagnets can propagate over mesoscopic distances without any charge transport involved, paving the way for green data processing. Therefore, using the electrons’ spin degree of freedom for data processing instead of its charge is one great challenge. Indeed, in the last decade intense research was made to explore the excitation, transport and manipulation as well as the detection of spin waves mostly in ferromagnetic thin-films. Recent progress in materials science however allows for the production of rolled-up and flexible three dimensional curved magnetic nano-membranes, such as nanotubes, spherical caps. The theoretical works predict that when the curvature radius reaches intrinsic length scales, like the domain wall width or the magnon wave length surprising effects may appear. In simple ferromagnets, the curvature induced magnetochiral effect can lead to the formation of chiral domain walls, stabilize magnetic textures as Skyrmions, or can result in non-reciprocal spin-wave propagation. The project tries to merge the spin-wave transport and the magnetochiral effects of exchange and classical dipole-dipole origin. The aim is to develop a fundamental understanding of the influence of the curvature and topology on the spin-wave transport in the three-dimensional curved structures within the framework of micromagnetism. The magnetochiral effect in curvilinear systems, originating from the symmetric exchange and/or dipole-dipole interactions brings further degrees of freedom into the transport and manipulation of spin waves. In addition, the curvilinear systems give the possibility to explore spin-wave transport in the third geometrical dimension. The variety of geometries considered within the proposal — transition from round to hexagonal nanotubes and to round nanowires as well as the ripple structures and all connected to the previously investigated magnetic nanotubes — are expected to bring effects which in long term perspective can contribute to extend the physical toolbox of spin-wave control and furthermore will promote the three-dimensional nano-membranes in the field of magnonics.