175 research outputs found

    Self-Energy Effects on the Low- to High-Energy Electronic Structure of SrVO3

    Full text link
    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-TcT_c cuprate superconductors: Universality from the Fermi arc picture

    Full text link
    We have performed a temperature dependent angle-resolved photoemission spectroscopy (ARPES) study of the tri-layer high-TcT_c cuprate superconductor (HTSC) Bi2_2Sr2_2Ca2_2Cu3_3O10+δ_{10+\delta} (Bi2223), and have shown that the \textquotedblleft effective\textquotedblright superconducting (SC) gap Δsc\Delta_{\rm{sc}} defined at the end point of the Fermi arc and the TcT_c (= 110 K) approximately satisfies the weak-coupling BCS-relationship 2Δsc\Delta_{\rm{sc}} = 4.3kBTck_{\rm{B}}T_c. Combining this result with previous ARPES results on single- and double-layer cuprates, we show that the relationship between 2Δsc\Delta_{\rm{sc}} = 4.3kBTck_{\rm{B}}T_c holds for various HTSCs. Furthermore, at TT ∼\sim TcT_c, the quasi-patricle width at the end point of the Fermi arc is found to coincide with Δsc\Delta_{\rm{sc}}, 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 Bi2_2Sr2_2Ca2_2Cu3_3O10+δ_{10+\delta}

    Full text link
    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 Bi2_2Sr2_2Ca2_2Cu3_3O10+δ_{10+\delta} (Bi2223). The kink energy of the OP band is ∼\sim 70 meV, as observed in various high-TcT_c 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 ∼\sim 35 meV buckling mode plus the large (∼\sim 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 ∼\sim 35 meV buckling-phonon mode plus the ∼\sim 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

    Full text link
    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
    • …
    corecore