Structural Dynamics (Mar 2024)

Transient grating spectroscopy on a DyCo5 thin film with femtosecond extreme ultraviolet pulses

  • Victor Ukleev,
  • Ludmila Leroy,
  • Riccardo Mincigrucci,
  • Dario De Angelis,
  • Danny Fainozzi,
  • Nupur Ninad Khatu,
  • Ettore Paltanin,
  • Laura Foglia,
  • Filippo Bencivenga,
  • Chen Luo,
  • Florian Ruske,
  • Florin Radu,
  • Cristian Svetina,
  • Urs Staub

DOI
https://doi.org/10.1063/4.0000223
Journal volume & issue
Vol. 11, no. 2
pp. 025101 – 025101-6

Abstract

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Surface acoustic waves (SAWs) are excited by femtosecond extreme ultraviolet (EUV) transient gratings (TGs) in a room-temperature ferrimagnetic DyCo5 alloy. TGs are generated by crossing a pair of EUV pulses from a free electron laser with the wavelength of 20.8 nm matching the Co M-edge, resulting in a SAW wavelength of Λ = 44 nm. Using the pump-probe transient grating scheme in reflection geometry, the excited SAWs could be followed in the time range of −10 to 100 ps in the thin film. Coherent generation of TGs by ultrafast EUV pulses allows to excite SAW in any material and to investigate their couplings to other dynamics, such as spin waves and orbital dynamics. In contrast, we encountered challenges in detecting electronic and magnetic signals, potentially due to the dominance of the larger SAW signal and the weakened reflection signal from underlying layers. A potential solution for the latter challenge involves employing soft x-ray probes, albeit introducing additional complexities associated with the required grazing incidence geometry.