Kwon Park 2009 New J. Phys. 11 073027 doi:10.1088/1367-2630/11/7/073027
Dynamical mean field theory of the repulsive BCS+U model
Kwon Park
Show affiliationsThe Gutzwiller-projected BCS Hamiltonian is a useful model for high-temperature superconductivity due to its equivalence to the Heisenberg model at half filling and a close connection to the t–J model at moderate doping. In this work, a dynamical mean field theory (DMFT) is developed for the BCS Hamiltonian with d-wave pairing subject to on-site repulsive interaction, U, which we call the BCS+U model. The large-U limit corresponds to the Gutzwiller-projected BCS Hamiltonian. It is shown that the equivalence between the Heisenberg and the Gutzwiller-projected BCS model is a manifestation of a broader duality in the BCS+U model: for any finite U, the local dynamics of the BCS+U model is dual at half filling with respect to the exchange between the hopping parameter, t, and the pairing amplitude, Δ. It is explicitly demonstrated in our DMFT analysis that the real superconducting gap, determined from the sharp coherence peaks in the local density of states, shows strong renormalization from its bare value as a function of U.
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GENERAL SCIENTIFIC SUMMARY
Introduction and background. High-temperature superconductivity in copper-oxide is arguably one of the most important problems in condensed matter physics. Its complete understanding, however, is still as elusive as it was more than twenty years ago when the phenomenon was first discovered. At the crux of the problem lies the intimate interplay between superconductivity and strong Coulomb correlation.Main results. To systematically investigate the interplay between superconductivity and strong Coulomb correlation, we study a model called the BCS+U Hamiltonian which is nothing but an effective Hamiltonian with built-in d-wave pairing amplitude competing against on-site repulsive interaction, U. As a result of the dynamical mean-field theory (DMFT) analysis of this model, it is shown that the real superconducting gap is strongly renormalized from the bare value as a function of U.
Wider implications. The results of this work have direct implications for a general class of unconventional superconductors which exhibit strong renormalization of the superconducting pairing gap and closely-related pseudogap phenomena.
- PACS
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74.20.Fg BCS theory and its development
74.72.-h Cuprate superconductors (high-Tc and insulating parent compounds)
- Subjects
- Dates
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Issue 7 (July 2009)
Received 4 February 2009
Published 15 July 2009
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Dynamical mean field theory of the repulsive BCS+U model
Kwon Park 2009 New J. Phys. 11 073027
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