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Phys. Rev. B 72, 212509 (2005) [4 pages]

High-Tc superconductivity due to coexisting wide and narrow bands: A fluctuation exchange study of the Hubbard ladder as a test case

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Kazuhiko Kuroki1, Takafumi Higashida1, and Ryotaro Arita2,*
1Department of Applied Physics and Chemistry, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
2Department of Physics, University of Tokyo, Hongo 7-3-1, Tokyo 113-0033, Japan

Received 26 August 2005; published 15 December 2005

We propose that when the Fermi level lies within a wide band and also lies close to but not within a coexisting narrow band, high-Tc superconductivity may take place due to the large number of interband pair scattering channels and the small renormalization of the quasiparticles. We show using the fluctuation exchange method that this mechanism works for the Hubbard model on a ladder lattice with diagonal hoppings. From this viewpoint, we give a possible explanation for the low Tc for the actual hole-doped ladder compound, and further predict a higher Tc for the case of electron doping.

© 2005 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevB.72.212509
DOI:
10.1103/PhysRevB.72.212509
PACS:
74.20.Mn, 74.62.−c

*Present address: Max Planck Institute for Solid State Research, Heisenbergstrasse 1, Stuttgart 70569, Germany.