ORCID Profile
0000-0003-0572-6735
Current Organisation
Elettra Sincrotrone Trieste SCpA
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Publisher: IOP Publishing
Date: 13-08-2013
Publisher: The Optical Society
Date: 14-11-2013
DOI: 10.1364/OE.21.028729
Publisher: SPIE
Date: 19-10-2012
DOI: 10.1117/12.930075
Publisher: American Physical Society (APS)
Date: 16-06-2017
Publisher: Springer Science and Business Media LLC
Date: 16-10-2014
DOI: 10.1038/NCOMMS6279
Publisher: MDPI AG
Date: 31-12-2020
DOI: 10.3390/APP11010325
Abstract: Ultrashort optical pulses can trigger a variety of non-equilibrium processes in magnetic thin films affecting electrons and spins on femtosecond timescales. In order to probe the charge and magnetic degrees of freedom simultaneously, we developed an X-ray streaking technique that has the advantage of providing a jitter-free picture of absorption cross-section changes. In this paper, we present an experiment based on this approach, which we performed using five photon probing energies at the Ni M2,3-edges. This allowed us to retrieve the absorption and magnetic circular dichroism time traces, yielding detailed information on transient modifications of electron and spin populations close to the Fermi level. Our findings suggest that the observed absorption and magnetic circular dichroism dynamics both depend on the extreme ultraviolet (XUV) probing wavelength, and can be described, at least qualitatively, by assuming ultrafast energy shifts of the electronic and magnetic elemental absorption resonances, as reported in recent work. However, our analysis also hints at more complex changes, highlighting the need for further experimental and theoretical studies in order to gain a thorough understanding of the interplay of electronic and spin degrees of freedom in optically excited magnetic thin films.
Publisher: Springer Science and Business Media LLC
Date: 22-08-2014
DOI: 10.1038/NCOMMS5661
Abstract: In X-ray Fourier-transform holography, images are formed by exploiting the interference pattern between the X-rays scattered from the s le and a known reference wave. To date, this technique has only been possible with a limited set of special reference waves. We demonstrate X-ray Fourier-transform holography with an almost unrestricted choice for the reference wave, permitting experimental geometries to be designed according to the needs of each experiment and opening up new avenues to optimize signal-to-noise and resolution. The optimization of holographic references can aid the development of holographic techniques to meet the demands of resolution and fidelity required for single-shot imaging applications with X-ray lasers.
Publisher: The Optical Society
Date: 19-10-2012
DOI: 10.1364/OE.20.025152
Publisher: AIP Publishing
Date: 09-2020
DOI: 10.1063/4.0000033
Abstract: Ultrafast phenomena on a femtosecond timescale are commonly examined by pump-probe experiments. This implies multiple measurements, where the s le 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 s le, 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-shell resonances 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. We furthermore observe that the electronic dynamics of Ni and Fe show pronounced differences when probed at their resonance, while the demagnetization dynamics are similar. 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.
Publisher: American Physical Society (APS)
Date: 13-06-2023
Publisher: Springer Science and Business Media LLC
Date: 29-10-2018
DOI: 10.1038/S41467-018-06743-8
Abstract: The invention of optical lasers led to a revolution in the field of optics and to the creation of such fields of research as quantum optics. The reason was their unique statistical and coherence properties. The emerging, short-wavelength free-electron lasers (FELs) are sources of very bright coherent extreme-ultraviolet and X-ray radiation with pulse durations on the order of femtoseconds, and are presently considered to be laser sources at these energies. FELs are highly spatially coherent to the first-order but in spite of their name, behave statistically as chaotic sources. Here, we demonstrate experimentally, by combining Hanbury Brown and Twiss interferometry with spectral measurements that the seeded XUV FERMI FEL-2 source does indeed behave statistically as a laser. The results may be useful for quantum optics experiments and for the design and operation of next generation FEL sources.
Publisher: Springer Science and Business Media LLC
Date: 13-11-2019
DOI: 10.1038/S41467-019-13249-4
Abstract: An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Publisher: The Optical Society
Date: 13-05-2013
DOI: 10.1364/OE.21.012385
Location: Italy
Location: United States of America
Location: Italy
No related grants have been discovered for Emanuele Pedersoli.