Time-resolved imaging with HERALDO.

本提案的目的是开发一种软x射线全息成像技术，用于千兆赫波段磁化动力学的时间分辨测量。PI最近展示了自相关线性微分算子（HERALDO）扩展参考全息术的首次应用，该全息术用于在亚微观磁性元素中以高空间分辨率成像“面内”和“面外”磁化磁畴。对直径在500 nm以内的坡莫合金薄膜元件的涡流结构进行了成像，分辨率为30 nm。作为一种无透镜技术，它被证明是免疫的机械振动和x射线束的漂移，以及元素特异性。在此，我们希望将该技术的能力扩展到基于自旋-转矩传递装置的涡振子的动态特性研究中。我们特别想探索基于纳米接触元件的自旋力矩涡振荡器（STVO）的旋转机理。这里的主要反对意见是为该技术增加皮秒时间分辨率，以便在旋转周期的不同阶段成像NC STVO的磁化配置。所获得的信息将增加对STVO操作的理解，并通过增加多个STVO设备的旋转幅度和锁相来提高频率和功率输出。为了实现和应用HERALDO的时间分辨测量，我们建议在同步加速器SOLEIL上进行光束线六分仪实验。PI最近在这条波束线上获得了18次波束时间偏移，计划于2014年6月投入使用。sexants是最近开放的光束线，提供高亮度偏振软x射线光束，用于使用弹性和非弹性散射进行测量。作为设备套装的一部分，sexants提供了使用傅里叶变换全息（FTH）成像的专用设置。作为一种衍射技术，HERALDO需要与FTH类似的实验安排，因此需要最小的修改。在实验的第一阶段（2014年6月），目标是在时间平均模式下测试该技术，届时将以连续模式测量涡旋结构。在实验的第二阶段，在下一轮的建议中，目的是在完全时间分辨模式下应用该技术。

The aim of this proposal is to develop a soft x-ray hologrphic imaging technique for time-resolved measurements of magnetisation dynamics in the GHz regime. PI has recently demonstrated the first application of Holography with Extended Reference by Autocorrelation Linear Differential Operator (HERALDO) that was used to image both 'in-plane' and 'out-of-plane' magnetised magnetic domains in submicroscopic magnetic elements with high spatial resolution. A vortex structure of permalloy thin film elements with diameters within 500 nm was imaged with a resolution of 30 nm. As a lensless technique it was shown to be immune to mechanical vabration and drift of the x-ray beam, as well as being element specific. Here we would like to extend the capability of this technique for studies of dynamic properties of vortex oscillators based on spin-torque transfer devices. In particular we would like to explore the gyration mechanisms of spin-torque vortex oscillators (STVO) based on nano-contact elements. The main objection here is to add picosecond temporal resolution to the technique in order to image magnetisation configuration of the NC STVO at different phases of the gyration cycle. The information gained will provide increased understanding of the operation of STVOs and lead to increased frequency and increased power output through increased amplitude of gyration and phase-locking of multiple STVO devices. In order to implement and apply the time-resolved measurments by HERALDO we propose to carry out experiments on the beamline SEXTANTS, at the synchrotron SOLEIL. The PI has recently been awarded 18 shifts of beam-time on this beam-line, which is scheduled for operation in June 2014. SEXTANTS is a recently opened beamline offering a high brilliance polarised soft x-ray beam for measurements using elastic and non-elastic scattering. As part of the equipment suit SEXTANTS provides a dedicated set-up for imaging using Fourier Transform Holography (FTH). As a diffraction technique HERALDO require similar experimental arrangements as FTH, thus will require minimum modification. In the first stage of the experiments (June 2014) the aim is to test the technique in time-averaged mode, when the vortex configurations will be measured in a continuous mode. In the second stage of the experiments, in the next round of proposals, the intention is to apply the technique in fully time-resolved mode.