利用Xfel源观测到的电荷密度波弯曲现象：一种可调谐的硬X射线电子透镜
Charge Density Wave bending observed by Xfel source acting as a tunable electronic lens for hard x-rays
AI总结：
本文利用LCLS自由电子激光发现低电流下电荷密度波波前会发生横向弯曲，该剪切效应可依据电流方向聚焦或散焦硬X射线，形成一种可在夫琅禾费区与菲涅耳区之间调谐的新型电子透镜，并用分数傅里叶变换解释其原理。
摘要：
利用LCLS自由电子激光进行的超快X射线衍射已被用于探测在外加电流作用下的电荷密度波（CDW）系统。在足够低的电流下，CDW波前在垂直于2k$_F$波矢的方向上发生弯曲。我们表明，这种剪切效应能够聚焦或散焦硬X射线束，具体取决于电流方向，从而构成一种新型电子透镜，可在夫琅禾费区到菲涅耳区之间任意调谐。该效应利用分数傅里叶变换进行解释，展示了纳米级调制的宏观曲率如何能够有益地用于改变X射线束的传播。
英文摘要：
Ultrafast X-ray diffraction by the LCLS free-electron laser has been used to probe Charge Density Wave (CDW) systems under applied external currents. At sufficiently low currents, CDW wavefronts bend in the direction transverse to the 2k$_F$ wave vector. We show that this shear effect has the ability to focus or defocus hard X-ray beams, depending of the current direction, making it an electronic lens of a new kind, tunable at will from the Fraunhofer to the Fresnel regime. The effect is interpreted using the fractional Fourier transform showing how the macroscopic curvature of a nanometric modulation can be beneficially used to modify the propagation of X-ray beams.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
