Time-domain imaging of curling modes in a confined magnetic vortex and a micromagnetic study exploring the role of spiral spin waves emitted by the core
Time-domain imaging of curling modes in a confined magnetic vortex and a micromagnetic study exploring the role of spiral spin waves emitted by the core
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DOI：
10.1103/physrevb.103.064408
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发表时间：
2020-07
期刊：
影响因子：
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通讯作者：
D. Osuna Ruiz;P. Keatley;J. Childress;J. Katine;R. Hicken;A. Hibbins;F. Ogrin
中科院分区：
文献类型：
--
作者：
D. Osuna Ruiz;P. Keatley;J. Childress;J. Katine;R. Hicken;A. Hibbins;F. Ogrin
利用时间分辨扫描克尔显微镜对微尺度圆盘中铁磁涡旋的卷曲自旋波模在微波场激励下进行了直接成像。微磁学模拟已被用来探索回旋涡核动力学的相互作用与卷曲模式中观察到的循环面内磁化区域。的基本gyrotropic模式与简并，最低频率，方位角模式的杂交先前已被报道，导致其分裂和反向传播运动，我们观察到在我们的光谱和测量的图像。的卷曲性质的模式可以归因于在整个磁盘厚度的静态和动态磁化的不对称性，但在这里，我们也提出了证据，螺旋自旋波发射的核心可以影响的空间特征的更高频率的卷曲模式的杂交只允许与gyrotropic模式的相同意义上的方位角运动。虽然它是具有挑战性的，以确定这种模式是真正的杂交从模式分散在一个封闭的磁盘，我们的模拟表明，螺旋自旋波从核心可以作为介质的核心动力学和方位角模式之间的相互作用。在更高的频率下，具有径向特征的模式仅不表现出明显的卷曲，而是显示出与在盘边缘产生的自旋波相互作用的证据。我们的模拟准确地再现了所观察到的卷曲模式的测量的时空特征，这揭示了从盘的核心和边缘区域传播的短波长螺旋自旋波的发射。我们的模拟表明，传播模式不是无关紧要的，但可能会发挥作用的核心和面内磁化区域的模式杂交所需的动态重叠。
The curling spin wave modes of a ferromagnetic vortex confined to a microscale disc have been directly imaged in response to a microwave field excitation using time-resolved scanning Kerr microscopy. Micromagnetic simulations have been used to explore the interaction of gyrotropic vortex core dynamics with the curling modes observed in the region of circulating in-plane magnetization. Hybridization of the fundamental gyrotropic mode with the degenerate, lowest-frequency, azimuthal modes has previously been reported to lead to their splitting and counter propagating motion, as we observe in our spectra and measured images. The curling nature of the modes can be ascribed to asymmetry in the static and dynamic magnetization across the disc thickness, but here we also present evidence that spiral spin waves emitted by the core can influence the spatial character of higher frequency curling modes for which hybridization is only permitted with gyrotropic modes of the same sense of azimuthal motion. While it is challenging to identify if such modes are truly hybridized from the mode dispersion in a confined disc, our simulations reveal that spiral spin waves from the core may act as mediators of the interaction between the core dynamics and azimuthal modes. At higher frequency, modes with radial character only do not exhibit marked curling, but instead show evidence of interaction with spin waves generated at the edge of the disc. The measured spatio-temporal character of the observed curling modes is accurately reproduced by our simulations, which reveal the emission of propagating short-wavelength spiral spin waves from both core and edge regions of the disc. Our simulations suggest that the propagating modes are not inconsequential, but may play a role in the dynamic overlap required for hybridization of modes of the core and in-plane magnetised regions.