An adaptive algorithm for n-body field expansions
Weinberg, Martin D.
1998-05-28
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Comment: to be published in the proceeding of the M2S-HTS - July 2006
Comment: Published version, 5 figs; published 29 July (2011)
The sudden change of the velocity, so-called "kink," of the dispersing peak
in angle resolved photoelectron spectroscopy is a well-known feature in the
high temperature superconducting cuprates. Currently, the origin of the kink is
being much debated, but a consensus has not emerged yet. Here, we present a
study of the momentum evolution of the kink structure from the nodal region
towards the anti-nodal region, for optimally doped Bi2212 sample. We show that
the observed temperature dependence of the kink structure in both regions of
the momentum space is consistent with a scenario in which phonons contribute
strongly to the kink.
Comment: 10 pages, 15 figures
A recent angle resolved photoelectron spectroscopy (ARPES) study by Douglas
et al. \cite {dessau-comment} on oxygen isotope exchanged
Bi_2Sr_2CaCu_2O$_{8+\delta}$ superconductors reported an absence of isotope
effect at optimal doping, questioning the previous work by us \cite
{gweon-nature}. Here, we report a new result that sheds light on this puzzling
discrepancy as well as the nature of the electron lattice interaction in the
cuprates: the anomalous isotope effect at optimal doping \cite {gweon-nature},
re-confirmed here, vanishes on a mere 2 % overdoping of holes. This result
implies a rapid change of the nature of the electron-lattice interaction near
optimal doping. We also find that the data by Douglas et al. \cite
{dessau-comment} are actually characteristic of significantly over-doped
samples, not of optimally doped samples...
Comment: 4 pages, 1 figure, submitted to SCES'01, figure font corrected
Comment: 5 pages, 2 figures, submitted to VUV-13
We discuss the nature of electron-lattice interaction in optimally doped
Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ samples, using isotope effect (IE) in angle
resolved photoemission spectroscopy (ARPES) data. The IE in the ARPES line
width and the IE in the ARPES dispersion are both quite large, implying a
strong electron-lattice correlation. The strength of the electron-lattice
interaction is ``intermediate,'' i.e. stronger than the Migdal-Eliashberg
regime but weaker than the small polaron regime, requiring a more general
picture of the ARPES ``kink'' than the commonly used Migdal-Eliashberg picture.
The two IEs also imply a complex interaction, due to their strong momentum
dependence and their differing sign behaviors. In sum, we propose an
intermediate-strength coupling of electrons to localized lattice vibrations via
charge density flu...
