The boson-fermion model: An exact diagonalization study

Abstract

The main features of a generic boson-fermion scenario for electron pairing in a many-body correlated fermionic system are: i) a cross-over from a poor metal to an insulator and finally a superconductor as the temperature decreases, ii) the build-up of a finite amplitude of local electron pairing below a certain temperature $T^{\ast }$, followed by the onset of long-range phase correlations among electron pairs below a second characteristic temperature $T_{\varphi }$, iii) the opening of a pseudogap in the DOS of the electrons below $T^{\ast }$, rendering these electrons poorer and poorer quasi-particles as the temperature decreases, with the electron transport becoming ensured by electron pairs rather than by individual electrons. A number of these features have been so far obtained on the basis of different many-body techniques, all of which have their built-in shortcomings in the intermediate coupling regime, which is of interest here. In order to substantiate these features, we investigate them on the basis of an exact diagonalization study on rings up to eight sites. Particular emphasis has been put on the possibility of having persistent currents in mesoscopic rings tracking the change-over from single- to two-particle transport as the temperature decreases and the superconducting state is approached.

7 pages, 8 figures; to be published in Phys. Rev. B

References in corpus (9)

• Plaquette Boson-Fermion Model of Cuprates
• Scaling theory of the Mott-Hubbard metal-insulator transition in one dimension
• Non-linear feedback effects in coupled Boson-Fermion systems
• Formation of a molecular Bose-Einstein condensate and an entangled atomic gas by Feshbach resonance
• On the pseudogap phase in high-T_c superconductors
• Precritical pair fluctuations and formation of a pseudogap in low-density nuclear matter
• Metal-insulator crossover in the Boson-Fermion model in infinite dimensions
• From local to macroscopic coherence in systems with composite quasi-particles
• From phase- to amplitude-fluctuation driven superconductivity in systems with precursor pairing

Cited by in corpus (10)

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• Bogoliubov shadow bands in the normal state of superconducting systems with strong pair fluctuations
• Superconductor-insulator transition driven by local dephasing
• Interplay between the single particle and collective features in the boson fermion model
• Diagrammatic Quantum Monte Carlo solution of the two-dimensional Cooperon-Fermion model
• Remnant superfluid collective phase oscillations in the normal state of systems with resonant pairing
• Full configuration interaction quantum Monte Carlo for coupled electron--boson systems and infinite spaces
• Resonant pairing isotope effect in polaronic systems
• Enhancement of pairing in a boson-fermion model for coupled ladders
• Dynamical local lattice instabilitiy triggered high tc superconductivity