Abstract
AbstractWe study the two‐dimensional Penson–Kolb model, i.e the tight‐binding model with the pair‐hopping interaction J, and analyze the effects of next‐nearest neighbour hopping t2 on the superconductivity in this system. In the analysis we focus on the properties of the superconducting state with Cooper‐pair center‐of‐mass momentum q = Q (eta‐phase), which can develop in this model for the case of repulsive J (J < 0) and q = 0 (s‐wave phase), which develops for the case of attractive J (J > 0). The evolutions of the phase diagrams, ground state characteristics and the transition temperatures with particle concentration and pairing strength are determined for square lattice. Within the Kosterlitz–Thouless scenario the Uemura‐type plots (Tc vs. 1/λ2(0)) are also derived. The results for t2 ≠ 0 are compared with those found for the case with nn hopping only. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
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