Concerning the nature of high-Tc superconductivity: Survey of experimental properties and implications for interlayer coupling

Abstract

An increasing body of data suggests the existence of a unique set of criteria characterizing ‘‘ideal’’ high-Tc superconductivity. Common to those materials exhibiting these high-Tc characteristics, i.e., the layered cuprates and certain layered organic superconductors, is the reduced dimensionality of the superfluid density. In cases where the carriers are confined to two dimensions, the parameters specifying the superconducting state would include the two-dimensional carrier density n2D, the interlayer spacing d, the two-dimensional effective mass mab*, the two-dimensional Fermi energy EF2D, and the average dielectric constant ε. To determine these parameters, we tabulate the relevant known properties on a variety of two- and three-dimensional superconductors. While partially limited by the quality of existing data, we nevertheless find that the data representative of the phase-pure high-Tc-like layered compounds of simple geometry, with stoichiometry optimized for minimum disorder effects and highest Tc, exhibit clean-limit correlations of the form n2Dd2=1, mab*∝ε/d, kBTc∝1/εd∝EF2D, and H1/2∝H0. Here, H0 is a characteristic field related to the upper critical field and H1/2 is the characteristic field at which the specific-heat jump at Tc is reduced to half its zero-field value. The observed correlations may be understood in terms of a simple interlayer Coulomb-coupling hypothesis.

Source-reported materials — not catalogue approval

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