Superconducting Properties of the η-Pairing State in the Penson-Kolb-Hubbard Model |
| W.R. Czart and S. Robaszkiewicz
Institute of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland |
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| The Penson-Kolb-Hubbard model, i.e. the Hubbard model with the pair-hopping interaction J is studied. We focus on the properties of the superconducting state with the Cooper-pair center-of-mass momentum q= Q (η-phase). The transition into theη-phase, which is favorized by the repulsive J (J<0) is found to occur only above some critical value |Jc|, dependent on band filling, on-site interaction U and band structure, and the system never exhibits standard BCS-like features. This is in obvious contrast with the properties of the isotropic s-wave state, stabilized by the attractive J and attractive U, which exhibit at T=0 a smooth crossover from the BCS-like limit to that of tightly bound pairs with increasing pairing strength. |
| DOI: 10.12693/APhysPolA.106.709 PACS numbers: 74.20.-z, 71.28.+d, 74.25.Ha |