Ultrafast magnetic scattering on ferrimagnets enabled by a bright Yb-based soft x-ray source

Fan, Guangyu; Légaré, Katherine; Cardin, Vincent; Xie, Xinhua; Safaei, Reza; Kaksis, Edgar; Andriukaitis, G.; Pugžlys, Audrius; Schmidt, Bruno E.; Wolf, Jean Pierre; Hehn, Michel; Malinowski, Grégory; Vodungbo, Boris; Jal, Emmanuelle; Lüning, J.; Jaouen, N.; Giovannetti, Gaia; Calegari, Francesca; Tao, Zhensheng; Baltuška, Andrius; Légaré, François; Balčiūnas, Tadas

doi:10.1364/optica.443440

Cited by 14 publications

(9 citation statements)

References 83 publications

(53 reference statements)

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“…As already suggested by Carva [22], "correctly" probing the magnetization might thus require an integration over the entire MCD spectrum (as intrinsically performed using broadband sources), and must be critically discussed in femtomagnetism experiments, where single, well-defined probing wavelengths are used [22]. This could explain why several studies, despite using comparable experimental conditions, reported rather different characteristic demagnetization times [41][42][43] and significant differences concerning the onset of demagnetization in material systems composed of multiple elements [44][45][46].…”

Section: Discussionmentioning

confidence: 98%

Time-Resolved XUV absorption spectroscopy and magnetic circular dichroism at the Ni $M_{2,3}$-edges

Hennes,

Rösner,

Chardonnet

et al. 2020

Preprint

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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 M 2,3 -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 charge and magnetic dynamics both depend on the 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 analysis in order to gain a thorough understanding of the interplay of electronic and spin degrees of freedom in optically excited magnetic thin films.

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Section: Discussionmentioning

confidence: 98%

Time-Resolved XUV absorption spectroscopy and magnetic circular dichroism at the Ni $M_{2,3}$-edges

Hennes,

Rösner,

Chardonnet

et al. 2020

Preprint

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show abstract

“…Attosecond pump-probe spectroscopy has emerged as a useful tool for probing and controlling ultrafast electronic dynamics in atoms [1][2][3][4][5][6][7][8][9][10][11][12][13][14], molecules [15][16][17][18][19][20][21][22], and condensed matter [23][24][25]. Above the ionization threshold, the electronic continuum of polyelectronic atoms and molecules feature localized states that are only transiently bound, since they can relax by Auger decay.…”

Section: Introductionmentioning

confidence: 99%

A Jaynes-Cummings-Fano Model for Autoionizing Polaritons

Cariker¹,

Yanez-Pagans²,

Harkema³

et al. 2022

Preprint

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Intense laser pulses can couple resonances in the continuum, giving rise to a split pair of autoionizing polaritons whose lifetime can be extended as a result of interference between radiative and Auger decay channels. We present an extension of the Jaynes-Cummings model to autoionizing states which quantitatively reproduces this phenomenology and allows us to study how the dressing laser parameters can be tuned to control the ionization rate of the polariton multiplet. We illustrate the potential of this model to estimate the splitting and widths of the polaritonic features in the attosecond transient absorption spectrum of the argon atom in the energy region close to the 3s −1 4p autoionizing state and compare the results with ab initio simulations of the spectrum in realistic experimental conditions.

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“…Extending the bright photon energy range of HHG is important for many applications in science and technology: First, bright and broadband soft x-ray radiation spans many element-specific absorption edges, e.g., the "water-window" energy, and enables table-top element-resolved spectroscopy and microscopy (13)(14)(15). Second, broader HHG bandwidths can support the generation of shorter attosecond pulses (16,17) or powerful broadband imaging and spectroscopy methods (18).…”

Section: Introductionmentioning

confidence: 99%

Extension of the bright high-harmonic photon energy range via nonadiabatic critical phase matching

Chen

Peng

et al. 2022

Sci. Adv.

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The concept of critical ionization fraction has been essential for high-harmonic generation, because it dictates the maximum driving laser intensity while preserving the phase matching of harmonics. In this work, we reveal a second, nonadiabatic critical ionization fraction, which substantially extends the phase-matched harmonic energy, arising because of the strong reshaping of the intense laser field in a gas plasma. We validate this understanding through a systematic comparison between experiment and theory for a wide range of laser conditions. In particular, the properties of the high-harmonic spectrum versus the laser intensity undergoes three distinctive scenarios: (i) coincidence with the single-atom cutoff, (ii) strong spectral extension, and (iii) spectral energy saturation. We present an analytical model that predicts the spectral extension and reveals the increasing importance of the nonadiabatic effects for mid-infrared lasers. These findings are important for the development of high-brightness soft x-ray sources for applications in spectroscopy and imaging.

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Ultrafast magnetic scattering on ferrimagnets enabled by a bright Yb-based soft x-ray source

Cited by 14 publications

References 83 publications

Time-Resolved XUV absorption spectroscopy and magnetic circular dichroism at the Ni $M_{2,3}$-edges

Time-Resolved XUV absorption spectroscopy and magnetic circular dichroism at the Ni $M_{2,3}$-edges

A Jaynes-Cummings-Fano Model for Autoionizing Polaritons

Extension of the bright high-harmonic photon energy range via nonadiabatic critical phase matching

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