Pairing mechanism in Bi-O superconductors: A finite-size chain calculation

A. A. Aligia; M. D. Nuez Regueiro; E. R. Gagliano

doi:10.1103/PhysRevB.40.4405

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Pairing mechanism in Bi-O superconductors: A finite-size chain calculation

A. A. Aligia, M. D. Nuez Regueiro, E. R. Gagliano

DOI 10.1103/PhysRevB.40.4405 · Physical Review B

T1

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Abstract

We have studied the pairing mechanism in BiO3 systems by calculating the binding energy of a pair of holes in finite Bi-O chains, for parameters that simulate three-dimensional behavior. In agreement with previous results using perturbation theory in the hopping t, for covalent Bi-O binding and parameters for which the parent compound has a disproportionate ground state, pairing induced by the presence of biexcitons is obtained for sufficiently large interatomic Coulomb repulsion. The analysis of appropriate correlation functions shows a rapid metallization of the system as t and the number of holes increase. This fact shrinks the region of parameters for which the finite-size calculations can be trusted without further study. The same model for other parameters yields pairing in two other regimes: bipolaronic and magnetic excitonic.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Ba1-x(K,Rb)xBiO3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	30	Pressure not reported	unknown
BaBiO3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown