882 research outputs found
Time-resolved photoemission of correlated electrons driven out of equilibrium
We describe the temporal evolution of the time-resolved photoemission
response of the spinless Falicov-Kimball model driven out of equilibrium by
strong applied fields. The model is one of the few possessing a metal-insulator
transition and admitting an exact solution in the time domain. The
nonequilibrium dynamics, evaluated using an extension of dynamical mean-field
theory, show how the driven system differs from two common viewpoints - a
quasiequilibrium system at an elevated effective temperature (the "hot"
electron model) or a rapid interaction quench ("melting" of the Mott gap) - due
to the rearrangement of electronic states and redistribution of spectral
weight. The results demonstrate the inherent trade-off between energy and time
resolution accompanying the finite width probe pulses, characteristic of those
employed in pump-probe time-domain experiments, which can be used to focus
attention on different aspects of the dynamics near the transition.Comment: Original: 5 pages, 3 figures; Replaced: updated text and figures, 5
pages, 4 figure
Comment on "Superconducting gap anisotropy vs. doping level in high-T_c cuprates" by C. Kendziora et al, PRL 77, 727 (1996)
In a recent paper Kendziora et al concluded that the superconducting gap in
overdoped Bi-2212 is isotropic. From data obtained from electronic Raman
scattering measurements, their conclusion was based on the observation that
pair breaking peaks occured at approximately the same frequency in different
scattering geometries and that the normalized scattering intensity at low
energies was strongly depleted. We discuss a different interpretation of the
raw data and present new data which is consistent with a strongly anisotropic
gap with nodes. The spectra can be successfully described by a model for Raman
scattering in a d_{x^{2}-y^{2}} superconductor with spin fluctuations and
impurity scattering included.Comment: 1 page revtex plus 1 postscript figur
Resonant Enhancement of Inelastic Light Scattering in Strongly Correlated Materials
We use dynamical mean field theory to find an exact solution for inelastic
light scattering in strongly correlated materials such as those near a
quantum-critical metal-insulator transition. We evaluate the results for
(Raman) scattering and find that resonant effects can be quite
large, and yield a triple resonance, a significant enhancement of nonresonant
scattering peaks, a joint resonance of both peaks when the incident photon
frequency is on the order of , and the appearance of an isosbestic point in
all symmetry channels for an intermediate range of incident photon frequencies.Comment: 5 pages RevTex, 4 Figures ep
Optical sum rules that relate to the potential energy of strongly correlated systems
A class of sum rules for inelastic light scattering is developed. We show
that the first moment of the non-resonant response provides information about
the potential energy in strongly correlated systems. The polarization
dependence of the sum rules provide information about the electronic
excitations in different regions of the Brillouin zone. We determine the sum
rule for the Falicov-Kimball model, which possesses a metal-insulator
transition, and compare our results to the light scattering experiments in
SmB_6.Comment: (5 pages, 3 figures, typeset in ReVTeX
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