Quantum percolation and lattice instabilities in high-Tc cuprate superconductors

Abstract

Lattice instabilities are the mechanisms that place upper bounds on Tc in theoretical models of superconductivity based on dynamical electron-phonon interactions. In percolative metals this upper bound can be much larger than in ballistic metals. For parameters appropriate to high-Tc cuprates, I show that the maximum value λ̃max of the percolative electron-phonon coupling constant is about four times larger than the value λmax∼1 appropriate to ballistic metals. I also review values of λ in ‘‘anomalous’’ ballistic metals, such as Nb3Ge homoepitaxial films, and show that these may be defect enhanced.

Source-reported materials — not catalogue approval

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