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Thermodynamic and electromagnetic properties of the Penson-Kolb model

2001; American Physical Society; Volume: 64; Issue: 10 Linguagem: Inglês

10.1103/physrevb.64.104511

1095-3795

W.R. Czart, S. Robaszkiewicz,

Quantum and electron transport phenomena

We study thermodynamic and electromagnetic properties of the Penson-Kolb model, i.e., the tight-binding model with the pair-hopping interaction J, and analyze the effects of phase fluctuations on the s-wave superconductivity in this system. The evolution of the critical fields, the coherence length, the Ginzburg ratio, and the London penetration depth \ensuremath{\lambda} with particle concentration n and pairing strength is determined at $T=0$ for d-dimensional hypercubic lattices $d=2$ (SQ) and $d=3$ (SC). Within the Kosterlitz-Thouless scenario the critical temperatures ${T}_{c}$ are calculated for $d=2$ SQ lattice and compared with the ones from BCS-HFA ${T}_{p}.$ The results show a substantial enhancement of the gap to critical temperature ratio due to the phase fluctuations as well as a separation of the energy scales for the pair formation $(\ensuremath{\sim}{k}_{B}{T}_{p})$ and the phase coherence $(\ensuremath{\sim}{k}_{B}{T}_{c}).$ The Uemura type plots, i.e., the ${T}_{c}$ vs ${\ensuremath{\lambda}}^{\ensuremath{-}2}(0)$ plots, are obtained both as a function of n and as a function of pairing strength. The results are compared with those found earlier for the attractive Hubbard model.