Article,
Accurate theoretical fits to laser-excited photoemission spectra in the normal phase of high-temperature superconductors
Nature Phys., (2008)
DOI: 10.1038/nphys833
Abstract
It has long been believed that the 'normal' (non-superconducting)
state of the high-transition-temperature superconductors is anything
but normal. In particular, this state, which exists above the superconducting
transition temperature Tc, has very unusual transport properties
and electron spectral functions, presenting a more difficult, complex
and important problem than the superconductivity itself. The origin
of this difficulty and complexity resides in the strong electronic
correlations, or the many-body Coulomb interactions between electrons,
which cannot be properly treated within the standard theories of
the electronic structure of solids. A new treatment of these interactions,
on the basis of a Gutzwiller projection—which gives zero quasiparticle
weight at the Fermi surface and removes the possibility for double
electron occupancy on any one site—has recently been proposed8, but
fits to available data were unsatisfactory. Here, we compare the
electron spectral functions computed within this theoretical treatment
with bulk-sensitive measurements made by low-energy photons, using
laser-excited angle-resolved photoemission spectroscopy of the superconductor
Bi2Sr2CaCu2O8+ . The theory captures the asymmetrical shape of the
experimental curves with good accuracy and in principle has only
one free parameter. Moreover, no background subtraction is necessary.
