Journal Article

PUBDB-2025-00512

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png First experiments with ultrashort, circularly polarized soft x-ray pulses at FLASH2

Marotzke, S.Extern*DESY* ; Gupta, D.Extern* ; Wang, R.-P.DESY* ; Pavelka, M.Extern* ; Dziarzhytski, S.DESY* ; von Korff Schmising, C.Extern* ; Jana, S. ; Thielemann-Kuehn, N.Extern* ; Amrhein, T.Extern* ; Weinelt, M.Extern* ; Vaskivskyi, I.Extern* ; Knut, R.Extern* ; Engel, D. ; Braune, M.DESY* ; Ilchen, M.CFEL*DESY* ; Savio, S.CFEL*Extern*XFEL.EU* ; Otto, T.DESY* ; Tiedtke, K.DESY* ; Scheppe, V. ; Rönsch-Schulenberg, J. ; Schneidmiller, E. A.DESY* ; Schuessler-Langeheine, C.Extern* ; Duerr, H.Extern* ; Beye, M.DESY* ; Brenner, G.DESY* ; Pontius, N. (Corresponding author)Extern*

2025
AIP Publishing LLC Melville, NY

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Please use a persistent id in citations: doi:10.1063/4.0000298  doi:10.3204/PUBDB-2025-00512

Abstract: Time-resolved absorption Spectroscopy as well as Magnetic Circular Dichroism with circularpolarized soft X-rays (XAS and XMCD) are powerful tools to probe electronic and magnetic dynamicsin magnetic materials in an element- and site selective manner. Employing these methods,groundbreaking results have been achieved for instance for magnetic alloys, which helped to fundamentallyadvance the field. The possibilities for ultrafast XAS and XMCD experiments, haverecently improved: In an upgrade of the free electron laser FLASH, a variable polarization afterburnerundulator at FLASH2 was installed in September 2023. This upgrade allows the generationof few tens of femtosecond short circularly polarized soft X-ray pulses covering the L2,3-edges of theimportant 3d transition metal elements. Here, we present first experimental results with circularlypolarized ultrashort X-ray pulses from the FL23 beamline employing XMCD at the L-edges of the3d elements, Co, Fe and Ni. We obtain significant XMCD, which hints to a degree of circular polarizationclose to 100%. Making use of the full pulse-length preserving monochromator capabilitiesof FL23 and an improved pump laser setup, FLASH offers important and efficient experimentalinfrastructure for ultrafast spin dynamics studies in 3d transition metals.

Note: Additional grant:Deutsche Forschungsgemeinschaft (DFG) - ProjectID 328545488 - TRR 227 “Ultrafast Spin Dynamics”.

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Contributing Institute(s):

1. DOOR-User (DOOR ; HAS-User)
2. FS-FLASH (FS-FLASH)
3. FLASH Photonen-Strahlführungen und Optiken (FS-FLASH-B)
4. FLASH Wissenschaftlicher Nutzerbetrieb (FS-FLASH-O)
5. X-ray Atto-Chirality (CFEL-XAC)

Research Program(s):

1. 631 - Matter – Dynamics, Mechanisms and Control (POF4-631) (POF4-631)
2. 6G2 - FLASH (DESY) (POF4-6G2) (POF4-6G2)
3. FS-Proposal: F-20211728 EC (F-20211728-EC) (F-20211728-EC)
4. FS-Proposal: F-20220710 (F-20220710) (F-20220710)
5. DFG project G:(GEPRIS)328545488 - TRR 227: Ultraschnelle Spindynamik (328545488) (328545488)

Experiment(s):

1. FLASH2 Beamline FL23 (FLASH2)

Appears in the scientific report 2025

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