175 research outputs found
Self-Energy Effects on the Low- to High-Energy Electronic Structure of SrVO3
The correlated electronic structure of SrVO3 has been investigated by
angle-resolved photoemission spectroscopy using in-situ prepared thin films.
Pronounced features of band renormalization have been observed: a sharp kink
~60 meV below the Fermi level (EF) and a broad so-called "high-energy kink"
~0.3 eV below EF as in the high-Tc cuprates although SrVO3 does not show
magnetic fluctuations. We have deduced the self-energy in a wide energy range
by applying the Kramers-Kronig relation to the observed spectra. The obtained
self-energy clearly shows a large energy scale of ~0.7 eV which is attributed
to electron-electron interaction and gives rise to the ~0.3 eV "kink" in the
band dispersion as well as the incoherent peak ~1.5eV below EF. The present
analysis enables us to obtain consistent picture both for the incoherent
spectra and the band renormalization.Comment: 5 pages, 3 figure
An energy scale directly related to superconductivity in the high- cuprate superconductors: Universality from the Fermi arc picture
We have performed a temperature dependent angle-resolved photoemission
spectroscopy (ARPES) study of the tri-layer high- cuprate superconductor
(HTSC) BiSrCaCuO (Bi2223), and have shown that
the \textquotedblleft effective\textquotedblright superconducting (SC) gap
defined at the end point of the Fermi arc and the (=
110 K) approximately satisfies the weak-coupling BCS-relationship
2 = 4.3. Combining this result with previous
ARPES results on single- and double-layer cuprates, we show that the
relationship between 2 = 4.3 holds for various
HTSCs. Furthermore, at , the quasi-patricle width at the end
point of the Fermi arc is found to coincide with , consistent
with the context of Planckian dissipation.Comment: 5 pages, 4 figure
Effect of electron-phonon coupling in the ARPES spectra of the tri-layer cuprate BiSrCaCuO
Angle-resolved photoemission spectroscopy using tunable low energy photons
allows us to study the quasi-particle (QP) dispersions of the inner and outer
CuO2 planes (IP and OP) separately in the tri-layer cuprate
BiSrCaCuO (Bi2223). The kink energy of the OP
band is 70 meV, as observed in various high- cuprates, while that
of the IP band is as large as 100 meV in the superconducting (SC) state. This
large kink energy is attributed to the 35 meV buckling mode plus the
large ( 60 meV) SC gap of IP. The IP band also shows a weak kink feature
at 70 meV in the SC state. The latter feature can be explained either by the 70
meV half-breathing mode or by the 35 meV buckling-phonon mode plus the
40 meV SC gap of OP if interlayer scattering of QP is involved.Comment: 5 pages, 2 figure
Formation of Omega Centauri by Tidal Stripping of a Dwarf Galaxy
We have investigated whether or not a tidal stripping scenario can reproduce
the observed surface-brightness profile of omega Centauri using N-body
simulations. Assuming that the progenitor of omega Centauri is a dwarf
elliptical galaxy, we model it with a King model with a core radius being the
same as that of omega Centauri. A dark matter halo of the dwarf is not taken
into account. We consider two different models of the Milky Way potential: a
singular isothermal sphere and a three-component model. The progenitor dwarf is
expressed as an N-body system, which orbits in the fixed Galactic potential.
The dwarf lost more than 90 per cent of its mass during the first few
pericenter passages. Thereafter, the mass remains practically constant. The
final surface-density profile is in good agreement with the observational data
on omega Centauri, if the pericenter distance of the orbit of the progenitor
dwarf is around 500 pc. This value is within the error bar of the current
proper motion data on omega Centauri and Galactic parameters. Although our
simulation is limited to a King-like progenitor dwarf without a dark matter
halo, it strongly suggests that the current density profile of omega Centauri
is nicely reproduced by a tidal stripping scenario, in other words, that omega
Centauri can plausibly be identified with a stripped dwarf elliptical.Comment: 15 pages, 2 tables, 4 figures. ApJL accepte
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