3D transport of spin waves in curved nano-membranes

铁磁体中的自旋波(或磁子)可以在介观范围内传播，而不涉及任何电荷传输，为绿色数据处理铺平了道路。因此，利用电子的自旋自由度而不是电荷进行数据处理是一个巨大的挑战。事实上，在过去的十年里，人们对铁磁薄膜中的自旋波的激发、输运和操纵以及检测进行了密集的研究。然而，材料科学的最新进展允许生产卷曲的和柔性的三维弯曲磁性纳米膜，如纳米管、球帽。理论工作预测，当曲率半径达到内禀长度尺度时，可能会出现磁化壁宽或磁振子波长等令人惊讶的效应。在简单的铁磁体中，曲率诱导的磁手征效应可以导致手征磁畴壁的形成，使磁织构稳定为Skyrmion，或者导致非互易自旋波的传播。该项目试图将交换和经典偶极-偶极起源的自旋波输运和磁手征效应结合起来。其目的是在微磁学的框架下，对曲率和拓扑对三维弯曲结构中自旋波输运的影响有一个基本的理解。曲线系统中源于对称交换和/或偶极-偶极相互作用的磁手征效应为自旋波的输运和操纵带来了更多的自由度。此外，曲线系统还提供了在第三几何维度上探索自旋波输运的可能性。建议中考虑的各种几何结构--从圆形到六边形纳米管和圆形纳米线以及波纹结构，以及所有这些结构都连接到以前研究的磁性纳米管--预计将带来从长远来看可能有助于扩展自旋波控制的物理工具箱的效果，并将进一步促进磁性材料领域的三维纳米膜的发展。

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.