论文标题
纳米级瞬态磁化光栅由飞秒极端紫外线激发和探测
Nanoscale transient magnetization gratings excited and probed by femtosecond extreme ultraviolet pulses
论文作者
论文摘要
我们利用源自自由电子激光器（FEL）的相干飞秒极端紫外线（EUV）脉冲来生成瞬时周期性磁化模式，周期短至44 nm。将空间周期性的激发与钴二分的谐音探测相结合，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。在驱逐驱逐的样本中，我们观察到一个接近FEL脉冲持续时间的50 fs上升时间的电子激发，并且在金属中电子波松弛范围内〜0.5 ps衰减时间。当实验在外部磁场中磁化为饱和的样品上进行实验时，我们会观察到磁化光栅，该磁化光栅以亚皮秒时间尺度出现，因为样品在EUV强度的最大值上消除了样品，然后通过热扩散在picseconds的Tens尺度上衰减。所描述的方法为研究纳米长度尺度上超快磁现象的动力学打开了前景。
We utilize coherent femtosecond extreme ultraviolet (EUV) pulses derived 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 dichroic 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 50 fs rise time close to the FEL pulse duration and ~0.5 ps decay time within the range for the electron-phonon relaxation in metals. When the experiment is performed on a sample magnetized to saturation in an external field, we observe a magnetization grating, which appears on a sub-picosecond 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 prospects for studying dynamics of ultrafast magnetic phenomena on nanometer length scales.
