HIGHT-Tc SUPERCONDUCTORS AS ALMOST-LOCALIZED SYSTEMS : RESONANCE AND FLUCTUATIONSReport as inadecuate




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Abstract : Many experimental results seem to relate the superconducting oxides to the phenomenon of Mott localization in strongly correlated systems. We will give a brief review of the different theories developed until then to treat the Mott localization in the Hubbard model : variational Ansatz of Gutzwiller or RVB Ansatz, leading to fundamentally different ground states. In this context, we propose a new approach which consists to take account of the quantum fluctuations around the mean-field solution provided by the Gutzwiller approximation. We show how to understand the ground state in terms of a resonance split by the Mott gap in the almost-localized regime in complete analogy with the Abrikosov-Suhl resonance of the Kondo problem - heavy fermions. Superconductivity appears as induced by the constrained intersite correlations developed by quantum fluctuations around this resonant state.





Author: M. Lavagna

Source: https://hal.archives-ouvertes.fr/



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