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

Müller, Leonard; Gutt, Christian; Streit-Nierobisch, S.; Walther, Michael; Schaffert, S.; Pfau, Bastian; Geilhufe, Jan; Büttner, Felix; Flewett, Samuel; Günther, C. M.; Eisebitt, Stefan; Kobs, A.; Hille, M.; Stickler, Daniel; Frömter, Robert; Oepen, Hans Peter; Lüning, J.; Grübel, G.

doi:10.1063/1.4773543

Cited by 3 publications

(3 citation statements)

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“…The photon energy was set to 59.6 eV corresponding to a wavelength of 20.8 nm to match the Co M 3 resonance. FEL pulse intensities were measured with a gas monitor [18] and the experiment was carried out in the chamber described in [19]. In Fig.…”

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Breakdown of the X-Ray Resonant Magnetic Scattering Signal during Intense Pulses of Extreme Ultraviolet Free-Electron-Laser Radiation

et al. 2013

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We present results of single-shot resonant magnetic scattering experiments of Co/Pt multilayer systems using 100 fs long ultraintense pulses from an extreme ultraviolet (XUV) free-electron laser. An x-ray-induced breakdown of the resonant magnetic scattering channel during the pulse duration is observed at fluences of 5 J/cm(2). Simultaneously, the speckle contrast of the high-fluence scattering pattern is significantly reduced. We performed simulations of the nonequilibrium evolution of the Co/Pt multilayer system during the XUV pulse duration. We find that the electronic state of the sample is strongly perturbed during the first few femtoseconds of exposure leading to an ultrafast quenching of the resonant magnetic scattering mechanism.

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Breakdown of the X-Ray Resonant Magnetic Scattering Signal during Intense Pulses of Extreme Ultraviolet Free-Electron-Laser Radiation

et al. 2013

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“…In order to investigate ultrafast demagnetization using FELs, a dedicated sample chamber was constructed allowing for optical-pump-FEL-probe measurements ( figure 3) at FLASH [19]. By employing the optical femtosecond laser available at FLASH, it was possible to probe the magnetic-domain system during the de-and remagnetization process [3].…”

Section: Resonant Scattering From Magnetic Domain Systemsmentioning

confidence: 99%

“…The decrease in domain width is caused by a change of the magnetic anisotropy of the multilayer system due to changes in its structure. Scanning-electron micrographs (figure 2) show that the FEL irradiation led to a recrystallization of the system.We note that owing to the large beam size, data can be taken non-destructively, however, the speckle pattern has a very fine structure with a typical size of 4 µm that cannot be resolved by the detector and the information about the local domain structure is lost.In order to investigate ultrafast demagnetization using FELs, a dedicated sample chamber was constructed allowing for optical-pump-FEL-probe measurements (figure 3) at FLASH [19]. By employing the optical femtosecond laser available at FLASH, it was possible to probe the magnetic-domain system during the de-and remagnetization…”

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Ultrafast Dynamics of Magnetic Domain Structures Probed by Coherent Free-Electron Laser Light

Müller

Schleitzer

Gutt

et al. 2013

Synchrotron Radiation News

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2 INTRODUCTIONThe free-electron laser (FEL) sources FLASH in Hamburg, LCLS at Stanford and FERMI in Trieste provide XUV to soft x-ray radiation (FLASH and FERMI) or soft to hard x-ray radiation (LCLS) with unprecedented parameters in terms of ultrashort pulse length, high photon flux, and coherence. These properties make FELs ideal tools for studying ultrafast dynamics in matter on a previously unaccessible level. This paper reviews first results obtained at FEL sources during the last years in the field of magnetism research. We start with pioneering experiments at FLASH demonstrating the feasibility of magnetic scattering at FELs [1,2], then present pump-probe scattering experiments [3,4] as well as the first FEL magnetic imaging experiments [5], and finally discuss a limitation of the scattering methods due to a quenching of the magnetic scattering signal by high-fluence FEL pulses [6]. All of the presented experiments exploit the x-ray magnetic circular dichroism effect [7,8] to obtain element-specific magnetic scattering contrast, as known from synchrotron experiments [9][10][11][12].One of the key problems in modern magnetism research, ultrafast demagnetization discovered by Beaurepaire in 1996 [13], acts on time scales of a few 100 fs, which are not accessible at standard synchrotron radiation sources. Since its discovery, ultrafast demagnetization was studied using optical femtosecond lasers, for a review see e. g.[14], and femtoslicing sources [15] at storage ring sources [16,17]. In both cases, spatial resolution is limited due to wavelength or flux limitations. In contrast, FELs combine high time resolution, element selectivity, and the spatial resolving power of xrays with high photon flux and excellent coherence properties. FEL sources, therefore, promise a pivotal step forward in the investigation of ultrafast phenomena on nanometer length scales. The rapid development of the FELs with respect to even shorter pulses, increased pulse stability, and special double-pulse schemes, e. g. for ultrafast movies [18], will open up exciting new opportunities in the field of material science. RESONANT SCATTERING FROM MAGNETIC DOMAIN SYSTEMSThe very first proof-of-principle resonant magnetic scattering experiment at x-ray FEL sources was carried out at FLASH in Hamburg [1]. In 2009 FLASH covered a photon energy range in the fundamental from 6.5 up to 50 nm with the routinely used cobalt L 3 -edge at 1.59 nm out of reach. However, by using the higher harmonics of the radiation 3 shorter wave length can be reached on the expense of photon flux. In this experiment FLASH was fine tuned to a fundamental wave length of 7.97 nm which results in the fifth harmonic located at the cobalt L 3 -edge. The scattering pattern from magnetic domains of a cobalt/palladium multilayer system with a perpendicular magnetic anisotropy and typical domain widths in the 100 nm range was recorded. This demonstrated that magnetic scattering as it is performed at synchrotron radiation sources is feasible at FELs. However, the fifth harmo...

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Sub-100 nanometer lensless probing of Co/Pd magnetic nanodomains using a table-top femtosecond soft X-ray harmonic source

Ducousso

Boutu

et al. 2013

Journal of Modern Optics

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International audienceWe present recent developments of our table-top femtosecond high flux harmonic beamline towards single-shot probing of magnetic nanostructures. High harmonic generation (HHG) optimization in a single and two-color infrared laser pulse mode was investigated at high laser energy. Up to 10(9) photons per harmonic are generated between 40 and 80 eV in a single femtosecond laser shot. These soft X-ray harmonic photons are employed to characterize at the nanoscale the magnetic network of Co/Pd multilayer samples using resonant small-angle X-ray scattering. Selecting harmonics in the vicinity of magnetically dichroic absorption resonances of cobalt and palladium (Co M-2,M-3 at 60eV and Pd N-2,N-3 at 51eV) gives access to the magnetic nanodomain spatial structure. The magnetic scattering efficiency at the Pd edge is found to be comparable to that at the Co edge. This indicates that the Pd layers exhibit a significant induced magnetic moment. Magnetic sample optimization is then performed by characterizing its scattering efficiency as a function of layer composition and number of repetitions. We finally measure the spatial organization of magnetic nanodomains with a sub-100nm spatial resolution from a single femtosecond X-ray pulse

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

Cited by 3 publications

References 52 publications

Breakdown of the X-Ray Resonant Magnetic Scattering Signal during Intense Pulses of Extreme Ultraviolet Free-Electron-Laser Radiation

Breakdown of the X-Ray Resonant Magnetic Scattering Signal during Intense Pulses of Extreme Ultraviolet Free-Electron-Laser Radiation

Ultrafast Dynamics of Magnetic Domain Structures Probed by Coherent Free-Electron Laser Light

Sub-100 nanometer lensless probing of Co/Pd magnetic nanodomains using a table-top femtosecond soft X-ray harmonic source

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