Session B33: Superconductivity: Mostly Cuprates

11:15 AM–2:15 PM, Monday, March 16, 2009
Room: 403

Sponsoring Unit: DCMP
Chair: Timir Datta, University of South Carolina

Abstract ID: BAPS.2009.MAR.B33.11

Abstract: B33.00011 : Competition between pairing and magnetic interactions

1:15 PM–1:27 PM

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  Raimundo dos Santos
    (Universidade Federal do Rio de Janeiro)

  Pedro Bertussi
    (Universidade Federal do Rio de Janeiro)

  Andre Malvezzi
    (Universidade Estadual Paulista)

  Thereza Paiva
    (Universidade Federal do Rio de Janeiro)

We discuss the interplay between pairing and magnetism by considering a model system composed of both tight-binding electrons and localized moments; the conduction electrons tend to form Cooper pairs due to a local (on-site) attractive interaction, $U$, while they also have a Kondo-like coupling, $J$, with the local moments. Density matrix renormalization group diagonalization on finite one-dimensional lattices (up to 60 sites) is used to calculate magnetic and pairing correlation functions, as well as structure factors in the ground state, in the case of electron density 1/3. Similarly to what happens in the quaternary borocarbides, we find that superconductivity coexists with a variety of magnetic arrangements of the local moments, ranging from commensurate to incommensurate spin-density waves, up to a critical value $J_c(U)$; the conduction electrons show strong antiferromagnetic fluctuations in this region. Superconductivity is then suppressed by the appearance of a magnetic state with broken rotational symmetry in both the local-moment and itinerant electrons subsystems, so that for sufficiently strong $J$, a spiral-ferromagnetic ground state evolves to a ferromagnetic one.

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