Critical Temperatures in the Three-Band Extended Hubbard Model

Górski, Grzegorz; Mizia, Jerzy; Kucab, Krzysztof

doi:10.1002/1521-3951(200010)221:2<703::aid-pssb703>3.0.co;2-2

Cited by 3 publications

(1 citation statement)

References 22 publications

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“…24͒, where the nearest-neighbor exchange interaction in the Heisenberg form J͚ ͗ij͘ S i · S j was added to the Hubbard model. For hightemperature superconducting compounds, for which there is more than one band involved in a given physical property, two-band 19,25-28 and three-band 23,[29][30][31][32][33][34][35] versions of the Hubbard model were used. Some authors ͑see Ref.…”

Section: Introductionmentioning

confidence: 99%

Hubbard model with intersite kinetic correlations

Górski

Mizia

2009

Phys. Rev. B

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We presented the intersite electron-electron correlation into the Hubbard III approximation. This correlation was excluded in the Hubbard III approximation and also in the equivalent coherent-potential approximation. Including it brings two spin-dependent effects: the bandwidth correction and the band shift correction, which both stimulate the ferromagnetic ground state. The band shift correction factor causes an exchange splitting between the spin-up and spin-down spectra, and its role is similar to the exchange interaction in the classic Stoner model. The spin-dependent bandwidth correction lowers the kinetic energy of electrons by decreasing the majority-spin bandwidth for some electron occupations with respect to the minority-spin bandwidth. In certain conditions it can lead to ferromagnetic alignment. A gain in the kinetic energy achieved in this way is the opposite extreme to the effect of a gain in potential energy due to exchange splitting. The band shift factor is a dominant force behind the ferromagnetism, but the presence of both factors working together is necessary to create spontaneous magnetization.

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Section: Introductionmentioning

confidence: 99%

Hubbard model with intersite kinetic correlations

Górski

Mizia

2009

Phys. Rev. B

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Role of Internal Stresses and Kinetic Energy Reduction in Layered Superconductors

Górski

Mizia

2002

phys. stat. sol. (b)

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74.20.Fg; 74.62.Fj We have considered an extended Hubbard model for the superconducting ceramics. The driving force for superconductivity in the single band model is the nearest-neighbour interaction augmented by the on-site and inter-site volume charge coupling. The transition to superconductivity is also supplemented by the decrease of kinetic energy obtained in the modified mean-field approximation, which is applied to the inter-site interactions. The BCS equation is solved numerically for the single band model with on-site and inter-site Coulomb interaction, and on-site and inter-site volume charge coupling. It is shown, that a physically reasonable set of electron-deformation coupling constants, together with kinetic energy decrease, will significantly lower the nearest-neighbour interaction required for the d-wave superconductivity.

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Itinerant Superconductivity

Mizia¹,

Górski²

2007

Models of Itinerant Ordering in Crystals

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Critical Temperatures in the Three-Band Extended Hubbard Model

Cited by 3 publications

References 22 publications

Hubbard model with intersite kinetic correlations

Hubbard model with intersite kinetic correlations

Role of Internal Stresses and Kinetic Energy Reduction in Layered Superconductors

Itinerant Superconductivity

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