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Pré-Publication, Document De Travail (Preprint/Prepublication) Année : 2020

Simultaneous two-color snapshot view on ultrafast charge and spin dynamics in a Fe-Cu-Ni tri-layer

Benedikt Rösner
Florian Döring
  • Fonction : Auteur
Vitaliy A. Guzenko
  • Fonction : Auteur
Armin Kleibert
  • Fonction : Auteur
Maxime Lebugle
  • Fonction : Auteur
Nicola Mahne
  • Fonction : Auteur
Denys Naumenko
  • Fonction : Auteur
Ivaylo P. Nikolov
  • Fonction : Auteur
Ignacio Lopez-Quintas
  • Fonction : Auteur
Emanuele Pedersoli
Primož R. Ribič
  • Fonction : Auteur
Tatiana Savchenko
  • Fonction : Auteur
Benjamin Watts
  • Fonction : Auteur
Marco Zangrando
  • Fonction : Auteur
Flavio Capotondi
  • Fonction : Auteur
Christian David

Résumé

Ultrafast phenomena on a femtosecond timescale are commonly examined by pump-probe experiments. This implies multiple measurements where the sample under investigation is pumped with a short light pulse and then probed with a second pulse at various time delays to follow its dynamics. Recently, the principle of streaking extreme ultraviolet (XUV) pulses in the temporal domain has enabled recording the dynamics of a system within a single pulse. However, separate pump-probe experiments at different absorption edges still lack a unified timing, when comparing the dynamics in complex systems. Here we report on an experiment using a dedicated optical element and the two-color emission of the FERMI XUV free-electron laser to follow the charge and spin dynamics in composite materials at two distinct absorption edges, simultaneously. The sample, consisting of ferromagnetic Fe and Ni layers, separated by a Cu layer, is pumped by an infrared laser and probed by a two-color XUV pulse with photon energies tuned to the M edges of these two transition metals. The experimental geometry intrinsically avoids any timing uncertainty between the two elements and unambiguously reveals an approximately 100 fs delay of the magnetic response with respect to the electronic excitation for both Fe and Ni. This delay shows that the electronic and spin degrees of freedom are decoupled during the demagnetization process. These observations underline the importance of simultaneous investigation of the temporal response of both charge and spin in multi-component materials. In a more general scenario, the experimental approach can be extended to continuous energy ranges, promising the development of jitter-free transient absorption spectroscopy in the XUV and soft X-ray regimes.

Dates et versions

hal-02870805 , version 1 (16-06-2020)

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Benedikt Rösner, Boris Vodungbo, Valentin Chardonnet, Florian Döring, Vitaliy A. Guzenko, et al.. Simultaneous two-color snapshot view on ultrafast charge and spin dynamics in a Fe-Cu-Ni tri-layer. 2020. ⟨hal-02870805⟩
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