Correlations between normal-state properties and superconductivity

Abstract

Despite many years of intense theoretical effort it is still not possible to predict whether a material will be superconducting or not at low temperatures by measurement of its physical properties at higher temperatures. Nor is it possible in general to estimate the magnitude of the superconducting critical temperature T c from measurements of normal-state properties. Here we address these questions from a statistical point of view. The metallic elements in the first six rows of the periodic table are assumed to be a ''representative sample'' drawn from a larger set of materials, and various statistical measures of correlations between the magnitude of T c and a normal-state property, as well as between a normal-state property and the fact whether the material is or is not a superconductor, are considered. Thirteen normal-state physical properties are studied, some of which are believed to be important to determine superconducting properties within conventional BCS theory and others not. It is found that properties assumed to be important within BCS theory rank lowest in predictive power regarding whether a material is or is not a superconductor. Instead, properties with highest predictive power in this respect are found to be bulk modulus, work function and Hall coefficient. With respect to the magnitude of T c , it is found to be positively correlated with electronic heat capacity, magnetic susceptibility, and atomic volume, and negatively correlated with electrical and thermal conductivity and Debye temperature. No significant correlations with ionic mass and ionization potential are found. Consequences of these findings for the theoretical understanding of superconductivity are discussed. ͓S0163-1829͑97͒01314-3͔

Spin-vortex Superconductivity

“…It is also worth noting that a statistical analysis reveals that the occurrence of superconductivity is strongly correlated to the fact that carriers are holes [20]. Since holes are known to become small polarons more frequently than electrons, the above-mentioned situation seems to fit the statistical analysis.…”

“…This is usually excused by the difficulty in obtaining normal state properties from which T c is calculated. However, it has been argued that the normal state properties that are important in predicting T c is not statistically correlated with whether a particular compound is a superconductor or not [20]. It is also observed in La 1.875 Ba 0.125 CuO 4 that although an energy gap that appears to be due to the Cooper-pair condensation exists, it fails to be superconducting [21].…”

Assembling the puzzle of superconducting elements: a review

“…11), implying that light elements are the best candidates for the utmost critical temperatures. Other correlations of T c with normal state properties [97], such as bulk modulus, work function, Hall coefficient, Debye temperature, etc. should be reevaluated in the light of the most recent findings in the critical temperature of simple elements.…”

Elastic properties and inter-atomic bonding in new superconductor from first principles calculations

“…Indeed, the elastic constants can be linked to such important physical parameters of superconductors (SCs) as the Debye temperature Θ D and the electron-phonon coupling constant λ [22]. Some others correlations between the superconducting critical temperature T C and mechanical parameters have been also discussed [23].…”