Photoemission linewidths and quasiparticle lifetimes

Smith, N. V.; Thiry, P.; Pétroff, Y.

doi:10.1103/physrevb.47.15476

Cited by 174 publications

(97 citation statements)

References 18 publications

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“…First, Lorentzians result provided both initial and final state bands disperse linearly across the direct emission photoelectron peak 14 . This is clearly violated at the X-point.…”

Section: B Linewidth Informationmentioning

confidence: 99%

“…The new experimental data for copper presented in this paper were obtained using one-photon photoemission spectroscopy 12,13 . This technique allows to determine lifetimes only from a detailed analysis of linewidths 14,15 , and requires simultaneously low temperatures, excellent energy as well as angular resolution and in general tunable photon energy. This expense is more than compensated by the very detailed understanding of the one-photon excitation channel and the possibility to locate a photo-hole exactly with respect to both initial-state energy E i and wave vector k. Recent calculations have shown that any reliable theory of hot-electron and hole lifetimes in metals must go beyond a free-electron description of the solid 16,17,18 .…”

Section: Introductionmentioning

confidence: 99%

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Lifetime ofdholes at Cu surfaces: Theory and experiment

et al. 2001

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We have investigated the hole dynamics at copper surfaces by high-resolution angle-resolved photoemission experiments and many-body quasiparticle GW calculations. Large deviations from a free-electron-like picture are observed both in the magnitude and the energy dependence of the lifetimes, with a clear indication that holes exhibit longer lifetimes than electrons with the same excitation energy. Our calculations show that the small overlap of d-and sp-states below the Fermi level is responsible for the observed enhancement. Although there is qualitative good agreement of our theoretical predictions and the measured lifetimes, there still exist some discrepancies pointing to the need of a better description of the actual band structure of the solid.

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“…First, Lorentzians result provided both initial and final state bands disperse linearly across the direct emission photoelectron peak 14 . This is clearly violated at the X-point.…”

Section: B Linewidth Informationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Lifetime ofdholes at Cu surfaces: Theory and experiment

et al. 2001

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“…17 In this way, the cross section can be thought of as the k Ќ convolution of two Lorentzians, where the imaginary part of k Ќ is the Lorentzian broadening. The curves in Fig.…”

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confidence: 99%

Periodicity and thickness effects in the cross section of quantum well states

et al. 2000

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The photoemission cross section of quantum well states in very thin Cu films has been analyzed as a function of photon energy within a wide energy range. We show that this cross section is periodical in k space, peaking around vertical transitions of the respective Cu bulk band. The cross section peak width is analyzed in terms of final-and initial-state wave vector broadening. The latter can only be detected at low kinetic energies due to reduction of final state broadening. The initial state k Ќ broadening increases when the Cu film gets thinner, as simply expected from the uncertainty principle.In a thin metal film deposited on a solid substrate electrons are confined in the perpendicular direction by the surface and interface potentials, leading to the formation of quantum well ͑QW͒ states. These are known to be responsible of intriguing phenomena in layered systems, like the oscillatory magnetic coupling of two magnetic layers across a nonmagnetic spacer 1 or the giant magnetoresistance. 2 Their existence has been frequently probed in noble and transition metals by means of angle-resolved photoemission 3 ͑ARPES͒ where they display strong energy-dependent cross sections. In general the QW cross section is expected to be maximum near vertical transitions of the bulk crystal of the material comprising the thin film. This reflects the conservation of the perpendicular wave vector in transitions from thin film states to final states in the continuum. 4 Such behavior has been qualitatively observed in Cu/Co͑100͒ ͑Ref. 5͒ and Ag/ Cu͑111͒ ͑Ref. 6͒. Away from this vertical transition region one can also obtain periodic modulations of the QW intensity. They have been attributed to discretization of the photoemission final-state band, 6 but also to surface-interface coherent photoemission effects. 7,8 Furthermore, it has been claimed that at low energies and very thin films such emission dominates over the regular QW photoemission from inside the thin film. 8 Here we show that this is not true for Cu films on Co͑100͒, since the cross section displays clear peaks around vertical transitions to the lowest three bulk final-state bands. The cross-section peak width is analyzed in terms of perpendicular wave vector broadening (⌬k Ќ ) for both final and initial ͑i.e., QW͒ states. The results show that the finalstate ⌬k Ќ dominates at h ϳ80 eV, whereas at h ϳ14 eV initial-state effects are necessary to explain the width of the transition peak. The thickness dependence of the initial state ⌬k Ќ and its magnitude appears to be related to confinement within the QW via the uncertainty principle.High-resolution photoemission experiments were done at the Synchrotron Radiation Center in Stoughton, Wisconsin (h Ͻ16 eV) and at the VUV photoemission beam line of the synchrotron radiation laboratory Elettra at Trieste, Italy (h Ͼ40 eV). In both cases the polarization of the synchrotron light was set to p-like in order to enhance sensitivity to ⌬ 1 -symmetry initial states. The photoemission spectra were normalized to the photon flux. ...

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“…However, even the most anisotropic cuprate systems possess some residual three-dimensionality, and the associated coupling between the CuO 2 layers in different unit cells yields dispersion of states with k z . In a 3D material, at a fixed value of k , k zdispersion leads to shifts in the position of the ARPES peak with photon energy (hν) [17]- [19]. The behaviour in a quasi-2D system is fundamentally different in that the spectral peaks will generally not shift with hν, but will instead display an irreducible linewidth which is a function of the in-plane momentum k [20,21].…”

Section: Introductionmentioning

confidence: 99%