We use time-resolved x-ray resonant magnetic scattering (TR-XRMS) at the Co $M_{2,3}$ and Tb $O_1$ edges to study ultrafast demagnetization in an amorphous ${\mathrm{Co}}_{88}{\mathrm{Tb}}_{12}$ alloy with stripe domains. Combining the femtosecond temporal with nanometer spatial resolution of our experiment, we demonstrate that the equilibrium spin texture of the thin film remains unaltered by the optical pump pulse on ultrashort timescales ($<1\mathrm{ps}$). However, after $\simeq 4$ ps, we observe the onset of a significant domain wall broadening, which we attribute to a reduction of the uniaxial magnetic anisotropy of the system, due to energy transfer to the lattice. Static temperature-dependent magnetometry measurements combined with analytical modeling of the magnetic structure of the thin film corroborate this interpretation.

中文翻译：

---

激光诱导的超快退磁和垂直磁各向异性在具有条带域的aCo88Tb12薄膜中的应用

我们在Co处使用时间分辨的X射线共振磁散射（TR-XRMS） ${\mathrm{中号}}_{2，3}$ 和Tb ${Ø}_{\mathrm{1个}}$ 边缘研究非晶态中的超快退磁 ${\mathrm{有限公司}}_{88}{b}_{12}$带条纹域的合金。将飞秒的时间与我们实验的纳米空间分辨率相结合，我们证明了薄膜的平衡自旋织构在超短时间尺度上不受光泵浦脉冲的影响而保持不变（$<\mathrm{1个}\mathrm{ps}$）。但是，之后$\simeq 4$ps，我们观察到明显的畴壁展宽的开始，这归因于由于能量转移到晶格，系统单轴磁各向异性的减小。静态温度相关的磁力测量与薄膜磁性结构的分析模型相结合，证实了这一解释。