Two Domains of the Parameter Space of the 2D Hubbard Model for High-Tc Superconductors |
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Authors: | K. Yamaji M. Miyazaki T. Yanagisawa |
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Affiliation: | (1) Nanoelectronics Research Institute, AIST Central 2, Tsukuba 305-8568, Japan;(2) Department of Physics, Aoyama Gakuin Univ., 5-10-1 Fuchinobe, Sagamihara 229-8558, Japan |
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Abstract: | High-T c superconducting cuprates have two types of Fermi surfaces: simple-2D-tight-binding-band type (LSCO type) and the much deformed one (Bi2212 type). The difference is attributed to that of band parameter values, i.e., t′ ∼ −0.1 and t″ ∼ 0 versus t′ ∼ −0.3 and t″ ∼ 0.2 in terms of the second- and third-neighbor transfer energies t′ and t″, respectively (energy unit is the nearest-neighbor transfer energy t). Assuming a moderate value of on-site Coulomb energy U ∼ 6 and performing the variational Monte Carlo computation, we found that the two superconducting parameter domains exist in fact around these parameter sets, respectively, in which superconductivity predominates over spin density wave (SDW) due to the latter being at the brink of vanishing. Stripes were obtained in the first domain but tend to disappear in the second. In the latter domain there seems to exist parameter sets for which superconductivity appears without doping. |
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Keywords: | Hubbard model cuprates stripes |
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