Exchange-torque-induced excitation of perpendicular standing spin waves in nanometer-thick YIG films.
Exchange-torque-induced excitation of perpendicular standing spin waves in nanometer-thick YIG films.
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DOI：
10.1038/s41598-018-23933-y
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发表时间：
2018-04-10
影响因子：
4.6
通讯作者：
van Dijken S
中科院分区：
文献类型：
--
作者：
Qin H;Hämäläinen SJ;van Dijken S
具有超低磁阻尼的亚铁磁钇铁石榴石（YIG）薄膜中的自旋波与基于磁振子的自旋电子学和低功率类波计算有关。由于YIG的饱和磁化强度小，在弱外磁场下，其自旋波的激发频率较低，限制了YIG薄膜在高频应用中的潜力。在这里，我们演示了如何交换耦合到CoFeB薄膜，使高效的激发高频垂直自旋驻波（PSSWs）在纳米厚（80 nm和295 nm）的YIG膜使用均匀的微波磁场。在295 nm厚的YIG薄膜中，我们测量了高达10阶的强PSSW模式。PSSW模式和CoFeB的铁磁共振模式之间的强杂化导致宽带自旋波谱中的特征反交叉行为。我们解释了PSSW的激发通过在YIG和CoFeB层中的强迫磁化进动之间的交换耦合。如果这些进动的振幅不同，则会产生动态交换力矩，导致从界面发射自旋波。当自旋波的波矢与垂直约束条件相匹配时，形成PSSW。如果通过10 nm Ta间隔层消除YIG和CoFeB之间的交换耦合，则PSSW不被激发。微磁学模拟证实了交换转矩驱动机制。
Spin waves in ferrimagnetic yttrium iron garnet (YIG) films with ultralow magnetic damping are relevant for magnon-based spintronics and low-power wave-like computing. The excitation frequency of spin waves in YIG is rather low in weak external magnetic fields because of its small saturation magnetization, which limits the potential of YIG films for high-frequency applications. Here, we demonstrate how exchange-coupling to a CoFeB film enables efficient excitation of high-frequency perpendicular standing spin waves (PSSWs) in nanometer-thick (80 nm and 295 nm) YIG films using uniform microwave magnetic fields. In the 295-nm-thick YIG film, we measure intense PSSW modes up to 10th order. Strong hybridization between the PSSW modes and the ferromagnetic resonance mode of CoFeB leads to characteristic anti-crossing behavior in broadband spin-wave spectra. We explain the excitation of PSSWs by exchange coupling between forced magnetization precessions in the YIG and CoFeB layers. If the amplitudes of these precessions are different, a dynamic exchange torque is generated, causing the emission of spin waves from the interface. PSSWs form when the wave vector of the spin waves matches a perpendicular confinement condition. PSSWs are not excited if exchange coupling between YIG and CoFeB is eliminated by a 10 nm Ta spacer layer. Micromagnetic simulations confirm the exchange-torque-driven mechanism.
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影响因子：
4.6
作者：
Hamalainen, Sampo J.;Brandl, Florian;van Dijken, Sebastiaan
通讯作者：
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影响因子：
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影响因子：
4.6
作者：
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通讯作者：
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影响因子：
8.6
作者：
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