Nanoscale Transient Magnetization Gratings Created and Probed by Femtosecond Extreme Ultraviolet Pulses
Nanoscale Transient Magnetization Gratings Created and Probed by Femtosecond Extreme Ultraviolet Pulses
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DOI：
10.1021/acs.nanolett.0c05083
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发表时间：
2021-03-16
期刊：
影响因子：
10.8
通讯作者：
Gutt, Christian
中科院分区：
文献类型：
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作者：
Ksenzov, Dmitriy;Maznev, Alexei A.;Gutt, Christian
我们利用自由电子激光器 (FEL) 的相干飞秒极紫外 (EUV) 脉冲来生成周期短至 44 nm 的瞬态周期性磁化图案。将空间周期性激励与钴 M 边缘的共振探测相结合，使我们能够在 CoGd 合金中创建和探测电子和磁激励的瞬态光栅。在退磁样品中，我们观察到电子激发，其上升时间接近 FEL 脉冲持续时间，并且类似于 0.5 ps 的衰减时间，表明电子声子弛豫。当样品在外场中磁化至饱和时，我们观察到磁化光栅，当样品在 EUV 强度最大值处消磁时，磁化光栅出现在亚皮秒时间尺度上，然后通过热扩散在数十皮秒时间尺度上衰减。所描述的方法为研究纳米长度尺度上的超快磁现象的动力学开辟了多种途径。
We utilize coherent femtosecond extreme ultraviolet (EUV) pulses from a free electron laser (FEL) to generate transient periodic magnetization patterns with periods as short as 44 nm. Combining spatially periodic excitation with resonant probing at the M-edge of cobalt allows us to create and probe transient gratings of electronic and magnetic excitations in a CoGd alloy. In a demagnetized sample, we observe an electronic excitation with a rise time close to the FEL pulse duration and similar to 0.5 ps decay time indicative of electron-phonon relaxation. When the sample is magnetized to saturation in an external field, we observe a magnetization grating, which appears on a subpicosecond time scale as the sample is demagnetized at the maxima of the EUV intensity and then decays on the time scale of tens of picoseconds via thermal diffusion. The described approach opens multiple avenues for studying dynamics of ultrafast magnetic phenomena on nanometer length scales.