Electron pairing mechanism in incipient ferroelectric BaPb1?x Bi x O3

Abstract

The lattice dynamical properties of BaPb1−xBixO3 are described within the polarizability model for perovskite oxides, but extended to take into account the valence instability of Bi. In a quantitative investigation it is found that a mode softening to a ferroelectric state is excluded, but a transition to a paired electron state is possible. The transformation of the classical Hamiltonian to its quantum-mechanical equivalent shows the parameter regimes for which pairing of electrons and thus possibly superconductivity occur.