Mayr Sina, Flajšman Lukáš, Finizio Simone, Hrabec Aleš, Weigand Markus, Förster Johannes, Stoll Hermann, Heyderman Laura J, Urbánek Michal, Wintz Sebastian, Raabe Jörg
Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
Laboratory for Mesoscopic Systems, Department of Materials, ETH Zurich, 8093 Zurich, Switzerland.
Nano Lett. 2021 Feb 24;21(4):1584-1590. doi: 10.1021/acs.nanolett.0c03740. Epub 2021 Feb 5.
We studied the influence of a static in-plane magnetic field on the alternating-field-driven emission of nanoscale spin waves from magnetic vortex cores. Time-resolved scanning transmission X-ray microscopy was used to image spin waves in disk structures of synthetic ferrimagnets and single ferromagnetic layers. For both systems, it was found that an increasing magnetic bias field continuously displaces the wave-emitting vortex core from the center of the disk toward its edge without noticeably altering the spin-wave dispersion relation. In the case of the single-layer disk, an anisotropic lateral expansion of the core occurs at higher magnetic fields, which leads to a directional rather than radial-isotropic emission and propagation of waves. Micromagnetic simulations confirm these findings and further show that focusing effects occur in such systems, depending on the shape of the core and controlled by the static magnetic bias field.
我们研究了静态面内磁场对磁涡旋核产生的纳米级自旋波的交变场驱动发射的影响。利用时间分辨扫描透射X射线显微镜对合成亚铁磁体和单铁磁层的盘状结构中的自旋波进行成像。对于这两种系统，均发现增加的磁偏置场会使发射波的涡旋核从盘中心持续向其边缘移动，而不会明显改变自旋波色散关系。在单层盘的情况下，在较高磁场下会出现核的各向异性横向扩展，这导致波的定向而非径向各向同性发射和传播。微磁模拟证实了这些发现，并进一步表明，在此类系统中会出现聚焦效应，这取决于核的形状并由静态磁偏置场控制。
