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2012 | 121 | 4 | 764-784
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Theory of Unconventional Superconductivity in Strongly Correlated Systems: Real Space Pairing and Statistically Consistent Mean-Field Theory - in Perspective

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In this brief overview we discuss the principal features of real space pairing as expressed via corresponding low-energy (t-J or periodic Anderson-Kondo) effective Hamiltonian, as well as consider concrete properties of those unconventional superconductors. We also rise the basic question of statistical consistency within the so-called renormalized mean-field theory. In particular, we provide the phase diagrams encompassing the stable magnetic and superconducting states. We interpret real space pairing as correlated motion of fermion pair coupled by short-range exchange interaction of magnitude J comparable to the particle renormalized band energy ≈ tx, where x is the carrier number per site. We also discuss briefly the difference between the real-space and the paramagnon-mediated sources of superconductivity. The paper concentrates both on recent novel results obtained in our research group, as well as puts the theoretical concepts in a conceptual as well as historical perspective. No slave-bosons are required to formulate the present approach.
  • Marian Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Kraków, Poland
  • Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Reymonta 19, 30-059 Kraków, Poland
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  • 47. One may therefore regard Hamiltonian ([E9]) as a reflecting strong-correlation limit of the fermion-boson model, in which the complex Bose field is with its total number of particles not conserved. For the fermion-boson model with the total number of bosons+fermions conserved, see e.g. J. Ranninger, S. Robaszkiewicz, Physica B 135, 468 (1985); T. Domański, J. Ranninger, Phys. Rev. Lett. 91, 255301 (2003). I am grateful to T. Domański for discussion of this model
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