We combine ultrafast X-ray diffraction (UXRD) and time-resolved Magneto-Optical Kerr Effect (MOKE) measurements to monitor the strain pulses in laser-excited TbFe2/Nb heterostructures. Spatial separation of the Nb detection layer from the laser excitation region allows for a background-free characterization of the laser-generated strain pulses. We clearly observe symmetric bipolar strain pulses if the excited TbFe2 surface terminates the sample and a decomposition of the strain wavepacket into an asymmetric bipolar and a unipolar pulse, if a SiO2 glass capping layer covers the excited TbFe2 layer. The inverse magnetostriction of the temporally separated unipolar strain pulses in this sample leads to a MOKE signal that linearly depends on the strain pulse amplitude measured through UXRD. Linear chain model simulations accurately predict the timing and shape of UXRD and MOKE signals that are caused by the strain reflections from multiple interfaces in the heterostructure.

中文翻译：

---

跟踪表现出巨大磁致伸缩的异质结构中的皮秒应变脉冲。

我们结合超快X射线衍射（UXRD）和时间分辨的磁光克尔效应（MOKE）测量来监视激光激发的TbFe2 / Nb异质结构中的应变脉冲。Nb检测层与激光激发区域的空间分隔允许对激光产生的应变脉冲进行无背景表征。如果被激发的TbFe2表面终止了样品，并且如果SiO2玻璃盖层覆盖了被激发的TbFe2层，则应变波包分解为不对称的双极和单极脉冲，我们可以清楚地观察到对称的双极应变脉冲。此样本中时间分离的单极应变脉冲的逆磁致伸缩导致MOKE信号线性依赖于通过UXRD测量的应变脉冲幅度。