Band-Resolved Double Photoemission Spectroscopy on Correlated Valence Electron Pairs in Metals

Trützschler, Andreas; Huth, Michael; Chiang, Cheng‐Tien; Kamrla, Robin; Schumann, F. O.; Kirschner, J.; Widdra, W.

doi:10.1103/physrevlett.118.136401

Cited by 21 publications

(12 citation statements)

References 44 publications

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“…Although not as clear as in the 2e DOS these spectra display changes in the slope. We have marked energy positions by arrows which roughly agree with the kink position of the 2e DOS and are also in agreement with a recent report on DPE from a Ag(100) surface obtained with a much better energy resolution [9]. The arrow at 5.3 eV in Fig.…”

Section: Photon Energy Dependence Ag(100)supporting

confidence: 91%

“…It turns out that the self-convolution of the electronic density of states becomes a better approximation for increasing photon energy. We find some fine structure in the sum energy spectrum similar to our previous reports with lower photon energies [9]. Near the high-energy cutoff we record a finite coincidence intensity.…”

Section: Introductionsupporting

confidence: 89%

“…While these factors are in the region as previously reported, we observe a clear photon energy dependence. This work covers a photon energy range from 40.8 to 60 eV, while the other work [9] used energies of 25.1 and 32.3 eV. Empirically we find that the 2e DOS becomes a better approximation upon increasing the photon energy.…”

Section: Photon Energy Dependence Ag(100)mentioning

confidence: 78%

“…There are also kinks where the slope abruptly changes, which occurs at E 2e B = 7.4 and 3.9 eV, respectively. The values define spectral regions labeled as d-d, sp-d, and sp-sp and different colors [9]. Near E 2e B = 0 the 2e DOS is determined by the low DOS of the 5sp electrons.…”

Section: Photon Energy Dependence Ag(100)mentioning

confidence: 99%

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Double photoemission from Ag and Pd surfaces: Energy relations

et al. 2020

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We have investigated the electron pair emission due to single-photon absorption from Ag(100) and Pd(100) surfaces. We are interested in the energy spectra of pairs in particular near the energy cutoff. The sum energy spectra of Ag display a distinctive photon energy dependence. We also observe some fine structure. Near the high-energy cutoff the coincidence rate is too low to determine the energy position of the cutoff. Nevertheless we observe a finite signal if two 5sp electrons near the Fermi level are emitted. For Pd(100) we find sum energy spectra without fine structure and the cutoff region is approached linearly. Within the experimental accuracy the minimum energy to liberate two electrons is twice the work function.

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Section: Photon Energy Dependence Ag(100)supporting

confidence: 91%

Section: Introductionsupporting

confidence: 89%

Section: Photon Energy Dependence Ag(100)mentioning

confidence: 78%

Section: Photon Energy Dependence Ag(100)mentioning

confidence: 99%

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Double photoemission from Ag and Pd surfaces: Energy relations

et al. 2020

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“…Two-particle correlations in photoemission have been used previously to study electronic interactions in equilibrium [24][25][26]. The process discussed here is an emission of two electrons by two photons from the same ultrashort pulse (different from a double photo-emission where one photon leads to the emission of two electrons due to secondary processes), and thus allows a theoretical interpretation along the same lines as the conventional theory for time-resolved photoemission spectroscopy [27][28][29].…”

mentioning

confidence: 95%

Noise correlations in time- and angle-resolved photoemission spectroscopy

Stahl

Eckstein

2019

Phys. Rev. B

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In time-resolved photoemission experiments, more than one electron can be emitted from the solid by a single ultra-short pulse. We theoretically demonstrate how correlations between the momenta of outgoing electrons relate to time-dependent two-particle correlations in the solid. This can extend the scope of time-and angular-resolved photoemission spectroscopy to probe superconducting and charge density fluctuations in systems without long-range order, and to reveal their dynamics independent of the electronic gap and thus unrestricted by the energy-time uncertainty. The proposal is illustrated for superconductivity in a BCS model. An impulsive perturbation can quench the gap on ultrafast timescales, while non-equilibrium pairing correlations persist much longer, even when electron-electron scattering beyond mean-field theory is taken into account. There is thus a clear distinction between a dephasing of the Cooper pairs and the thermalization into the normal state. While a measurement of the gap would be blind to such pairing correlations, they can be revealed by the angular correlations in photoemission. arXiv:1812.09222v1 [cond-mat.str-el]

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Imaging Momentum–Space Two‐Particle Correlations at Surfaces

Schumann

Kirschner

Berakdar

2020

Physica Status Solidi (b)

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Photoelectron and electron energy loss spectroscopies have been highly instrumental in revealing the various facets of electronic properties of materials. For a direct insight into two‐particle correlations, a technique is needed that resolves two emitted electrons in coincidence. Herein, an overview on the experimental realization of correlation spectroscopy and the interpretation of the recorded spectra from theory is provided. The relation of the measured spectra to the details of the spin‐, energy‐ and wavevector‐resolved electron–electron interactions is focused upon. To disentangle the contributions of exchange from the charge‐density correlation, positrons instead of electrons are used as projectiles. The short intrinsic time of the Auger decay and the neutralization of ions near a surface are used to estimate the characteristic timescale for the correlated electron dynamics in metals to be 40–400 attoseconds. The potential of conducting double photoemission studies with pulsed laser‐based light sources is addressed.

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Band-Resolved Double Photoemission Spectroscopy on Correlated Valence Electron Pairs in Metals

Cited by 21 publications

References 44 publications

Double photoemission from Ag and Pd surfaces: Energy relations

Double photoemission from Ag and Pd surfaces: Energy relations

Noise correlations in time- and angle-resolved photoemission spectroscopy

Imaging Momentum–Space Two‐Particle Correlations at Surfaces

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