Pseudospin Models of Superconductors with Very Short Coherence Length

S. Robaszkiewicz Institute of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland

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We discuss a few models developed for description of superconductivity with very short coherence length and point out their formal equivalence to specific spin models, such as an anisotropic Heisenberg model (s = 1/2) with two- and four-spin exchange coupling and with fixed magnetization in the z-direction, an XY-Z model with single ion anisotropy and a Kondo-lattice model with anisotropic on-site exchange. New results concerning the phase diagram of the Hubbard model with strong attraction, the electromagnetic properties of systems with the first order superconducting transition and a possibility of local charge moment compensation in systems of coexisting bound pairs and itinerant electrons are presented.

DOI: 10.12693/APhysPolA.85.117 PACS numbers: 74.20.-z, 05.30.Jp, 71.28.+d