Endstation for ultrafast magnetic scattering experiments at the free-electron laser in Hamburg

This content may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This material originally appeared in Review of Scientific Instruments 84, 013906 (2013) and may be found at https://doi.org/10.1063/1.4773543.An endstation for pump–probe small-angle X-ray scattering (SAXS) experiments at the free-electron laser in Hamburg (FLASH) is presented. The endstation houses a solid-state absorber, optical incoupling for pump–probe experiments, time zero measurement, sample chamber, and detection unit. It can be used at all FLASH beamlines in the whole photon energy range offered by FLASH. The capabilities of the setup are demonstrated by showing the results of resonant magnetic SAXS measurements on cobalt-platinum multilayer samples grown on freestanding Si3N4 membranes and pump-laser-induced grid structures in multilayer samples.BMBF, 05K10GU4, Verbundprojekt: FSP 301 - FLASH: Nanoskopische Systeme. Teilprojekt 6: Aufbau einer Plattform für Experimente mit ultimativer Orts- und Zeitauflösung unter Ausnutzung der kohärenten Beugung weicher Röntgenstrahlung an PETRA III und FLASHDFG, 13002249, SFB 668: Magnetismus vom Einzelatom zur NanostrukturDFG, 170620586, SFB 925: Licht-induzierte Dynamik und Kontrolle korrelierter Quantensystem

Imaging the in-plane magnetization in a Co microstructure by Fourier transform holography

We report on experiments using Fourier transform holography to image the in-plane magnetization of a magnetic microstructure. Magnetic sensitivity is achieved via the x-ray magnetic circular dichroism effect by recording holograms in transmission at off-normal incidence. The reference beam is defined by a narrow hole milled at an inclined angle into the opaque mask. We present magnetic domain images of an in-plane magnetized cobalt element with a size of 2 μm × 2 μm× 20 nm. The domain pattern shows a multi-vortex state that deviates from the simple Landau ground state

Magnetic soft X-ray holography study of focused ion beam-patterned Co/Pt multilayer

We report on Fourier transform holographyFTHexperiments on nanostructured Co/Pt multilayerfilms with 40 nm spatial imaging resolution. The films have been nanostructured by means offocused ion beamFIBmilling. Applying the ion beam through the supporting membrane withcontrolled and homogeneous dosing allows for higher resolution magnetic structuring of theion-sensitive film compared to direct FIB patterning. Nanostructured samples with magnetic stripesexposed to different ion doses and magnetic arrays with 200 nm lattice constant were successfullyprepared and imaged by FTH. We present image-processing routines for artifact-free imagereconstruction. With this, we could investigate the FIB-induced anisotropy modulation and theperpendicular domain structure in the nanostructured samples, showing how to control the domainsize and configuration by applying the appropriate ion dose either homogeneously or concentratedin single spot

Single-pulse resonant magnetic scattering using a soft x-ray free-electron laser

We report on single-pulse resonant magnetic scattering experiments using soft x-ray pulses generated by the free-electron laser FLASH at DESY. We could record a magnetic diffraction pattern from a Co/Pt multilayer sample at the Co M2,3 edge with a single 30-fs-long FEL pulse. The analysis of the magnetic small-angle scattering signal for subsequent pulses indicates a threshold energy density below which there is no indication that the magnetic properties of the sample might be altered

Magnetic imaging by x-ray holography using extended references

Copyright © 2011 OSAThis paper was published in Optics Express and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-19-17-16223. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.We demonstrate magnetic lensless imaging by Fourier transform holography using extended references. A narrow slit milled through an opaque gold mask is used as a holographic reference and magnetic contrast is obtained by x-ray magnetic circular dichroism. We present images of magnetic domains in a Co/Pt multilayer thin film with perpendicular magnetic anisotropy. This technique holds advantages over standard Fourier transform holography, where small holes are used to define the reference beam. An increased intensity through the extended reference reduces the counting time to record the farfield diffraction pattern. Additionally it was found that manufacturing narrow slits is less technologically demanding than the same procedure for holes. We achieve a spatial resolution of ∼30 nm, which was found to be limited by the sample period of the chosen experimental setup