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@ARTICLE{Fan:476742,
      author       = {Fan, Guangyu and Légaré, K. and Cardin, V. and Xie,
                      Xinhua and Safaei, R. and Kaksis, E. and Andriukaitis, G.
                      and Pugžlys, A. and Schmidt, B. E. and Wolf, J. P. and
                      Hehn, M. and Malinowski, G. and Vodungbo, B. and Jal,
                      Emmanuelle and Lüning, J. and Jaouen, N. and Giovannetti,
                      G. and Calegari, F. and Tao, Z. and Baltuška, A. and
                      Légaré, F. and Balciunas, Tadas},
      title        = {{U}ltrafast magnetic scattering on ferrimagnets enabled by
                      a bright {Y}b-based soft x-ray source},
      journal      = {Optica},
      volume       = {9},
      number       = {4},
      issn         = {2334-2536},
      address      = {Washington, DC},
      publisher    = {OSA},
      reportid     = {PUBDB-2022-01870},
      pages        = {399 - 407},
      year         = {2022},
      abstract     = {Development of ultrafast table-top x-ray sources that can
                      map various spin, orbital, and electronic configurations and
                      reordering processes on their natural time and length scales
                      is an essential topic for modern condensed matter physics as
                      well as ultrafast science. In this work, we demonstrate
                      spatiotemporally resolved resonant magnetic scattering
                      (XRMS) to probe the inner-shell 4d electrons of a rare-earth
                      (RE) composite ferrimagnetic system using a bright >200eV
                      soft x-ray high harmonic generation (HHG) source, which is
                      relevant for future energy-efficient, high-speed spintronic
                      applications. The XRMS is enabled by direct driving of the
                      HHG process with power-scalable, high-energy Yb laser
                      technology. The optimally phase-matched broadband plateau of
                      the HHG offers a record photon flux $(>2×109photons/s/1\%$
                      bandwidth) with excellent spatial coherence and covers the
                      entire resonant energy range of RE’s N4,5 edges. We verify
                      the underlying physics of our x-ray generation strategy
                      through the analysis of microscopic and macroscopic
                      processes. Using a CoTb alloy as a prototypical
                      ferrimagnetic system, we retrieve the spin dynamics, and
                      resolve a fast demagnetization time of 500±126fs,
                      concomitant with an expansion of the domain periodicity,
                      corresponding to a domain wall velocity of ∼750m/s. The
                      results confirm that, far from cross-contamination of
                      low-energy absorption edges in multi-element systems, the
                      highly localized states of 4d electrons associated with the
                      N4,5 edges can provide high-quality core-level magnetic
                      information on par with what can be obtained at the M edges,
                      which is currently accessible only at large-scale x-ray
                      facilities. The analysis also indicates the rich material-,
                      composition-, and probing-energy-dependent driving mechanism
                      of RE-associated multicomponent systems. Considering the
                      rapid emergence of high-power Yb lasers combined with novel
                      nonlinear compression technology, this work indicates
                      potential for next-generation high-performance soft x-ray
                      HHG-based sources in future extremely photon-hungry
                      applications on the table-top scale, such as probing
                      electronic motion in biologically relevant molecules in
                      their physiological environment (liquid phase), and advanced
                      coherent imaging of nano-engineered devices with 5∼8nm
                      resolution.},
      cin          = {FS-ATTO},
      ddc          = {620},
      cid          = {I:(DE-H253)FS-ATTO-20170403},
      pnm          = {631 - Matter – Dynamics, Mechanisms and Control
                      (POF4-631)},
      pid          = {G:(DE-HGF)POF4-631},
      experiment   = {EXP:(DE-MLZ)External-20140101},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000786174500010},
      doi          = {10.1364/OPTICA.443440},
      url          = {https://bib-pubdb1.desy.de/record/476742},
}