From phase- to amplitude-fluctuation driven superconductivity in systems with precursor pairing

Abstract

The change-over from phase- to amplitude-fluctuation driven superconductivity is examined for a composite system of free electrons (Fermions with concentration n_F) and localized electron-pairs (hard-core Bosons with concentration n_B) as a function of doping-changing n_B. The coupling together of these two subsystems via a charge exchange term induces electron pairing below a certain T^* (showing up in form of a pseudogap) and ultimately superconductivity in the Fermionic subsystem. T^* steadily decreases with decreasing n_B. Below T^* this electron pairing leads to electron-pair resonant states (Cooperons) with quasi-particle features which strongly depend on $n_B$. For high concentrations, (n_B \simeq 0.5), correlation effects between the hard-core Bosons lead to itinerant Cooperons having a heavy mass m_p, but are long-lived. Upon reducing n_B, the mass as well as the lifetime of those Cooperons is considerably reduced. For high values of n_B, a superconducting state sets in at a T_c, being controlled by the phase stiffness D_ϕ=\hbar^2 n_p/m_p of those Cooperons, where n_p denotes their density. Upon reducing n_B, the phase stiffness steadily increases, and eventually exceeds the pairing energy k_B T^*. The Cooperons loose their well defined itinerant quasi-particle features and superconductivity gets controlled by amplitude fluctuations. The resulting phase diagram with doping is reminiscent of that of the phase fluctuation scenario for high T_c superconductivity, except that in our scenario the determinant factors are the mass and the lifetime of the Cooperons rather than their density.

13 pages, 12 figures

References in corpus (26)

• The pseudogap in high-temperature superconductors: an experimental survey
• Vanishing of phase coherence in underdoped Bi_2Sr_2CaCu_2O_8+d
• Non-perturbative many-body approach to the Hubbard model and single-particle pseudogap
• Evidence for coexistence of the superconducting gap and the pseudo - gap in Bi-2212 from intrinsic tunneling spectroscopy
• Bosonic Mode Mixing in the Superconducting State Spectral Function of Bi_2Sr_2CaCu_2O_{8+delta}
• Plaquette Boson-Fermion Model of Cuprates
• Closing the Pseudogap by Zeeman Splitting in Bi_2Sr_2CaCu_2O_8+y at High Magnetic Fields
• Effective action for Superconductors and BCS-Bose crossover
• Doping dependence of the Fermi surface in Bi(Pb)2212
• Surprises in the doping dependence of the Fermi surface in Bi(Pb)-2212
• Non-interacting Cooper pairs inside a pseudogap
• Pairing fluctuations and pseudogaps in the attractive Hubbard model
• Non-linear feedback effects in coupled Boson-Fermion systems
• Pair fluctuation induced pseudogap in the normal phase of the two-dimensional attractive Hubbard model at weak coupling
• On the pseudogap phase in high-T_c superconductors
• Impurity induced resonant state in a pseudogap state of a high temperature superconductor
• The same superconducting criticality for underdoped and overdoped La_{2-x}Sr_xCuO_4 single crystals
• Precritical pair fluctuations and formation of a pseudogap in low-density nuclear matter
• Andreev reflections in the pseudogap state of cuprate supercondcutors
• c-Axis Superfluid Response and Pseudogap in High-Tc Superconductors
• Role of symmetry and dimension on pseudogap phenomena
• Metal-insulator crossover in the Boson-Fermion model in infinite dimensions
• Gorkov equations for a pseudo-gapped high temperature superconductor
• From local to macroscopic coherence in systems with composite quasi-particles
• The electronic specific heat in the pairing pseudogap regime
• Bound pair states beyond the condensate for Fermi systems below T_c: the pseudogap as a necessary condition

Cited by in corpus (9)

• Resonance effects on the crossover of bosonic to fermionic superfluidity
• Superconductor-insulator transition driven by local dephasing
• Interplay between the single particle and collective features in the boson fermion model
• The boson-fermion model: An exact diagonalization study
• Boson-Fermion Duality and Metastability in Cuprate Superconductors
• On the Boson-Fermion resonant model on a lattice
• Resonant pairing isotope effect in polaronic systems
• Effect of boson on-site repulsion on the superfluidity in the boson-fermion-Hubbard model
• Bosonic mode interpretation of novel STM and related experimental results, within boson-fermion modelling of HTSC Materials