Relationship between the isotope effects on transition temperature, specific heat and penetration depths

Abstract

We show that in anisotropic superconductors, falling at finite temperature into the 3D-XY- and at zero temperature into the 2D-XY-QSI universality class, the isotope effects on transition temperature, specific heat and magnetic penetration depths are not independent, but related by universal relations. The corresponding experimental data for cuprate superconductors reveals suggestive consistency with these relations. They imply a dominant role of fluctuations so that pair formation and pair condensation do not occur simultaneously. For this reason and due to the occurrence of the 2D-XY-QSI transition the isotope effects do not provide information on the underlying pairing mechanism but must be attributed to a shift of the phase diagram upon isotope substitution. The 2D-QSI transition is driven by the exchange of pairs, which favors superconductivity and the combined effects of disorder and Coulomb repulsion of the pairs, which favor localization. Since isotope substitution will hardly affect disorder and Coulomb repulsion, the shift of the phase diagram must be attributed to the electron-phonon interaction, which renormalizes the mass of the fermions and with that the mass and the exchange of the pairs.

10 pages, 5 figures

References in corpus (3)

• Universal properties of cuprate superconductors
• The oxygen isotope effect in the ab-plane reflectance of underdoped YBa_2Cu_3O_{7-delta}
• Competition between anisotropy and superconductivity in organic and cuprate superconductors

Cited by in corpus (10)

• Correlation between oxygen isotope effects on the transition temperature and the magnetic penetration depth in high-temperature superconductors close to optimal doping
• Probing inhomogeneities in type II superconductors by means of thermal fluctuations, magnetic fields and isotope effects
• Isotope effects in the Hubbard-Holstein model within dynamical mean-field theory
• Evidence for Kosterlitz-Thouless and 3D-xy critical behavior in Bi2212
• Implications evinced by the phase diagram, anisotropy, magnetic penetration depths, isotope effects and conductivities of cuprate superconductors
• Relationship between and implications of the isotope and pressure effects on transition temperature, penetration depths and conductivities
• Evidence for 3D-xy critical properties in underdoped YBa2Cu3O7+x
• Pressure effects on the superconducting properties of YBa_2Cu_4O_8
• Magnetic field induced 3D to 1D crossover in type II superconductors
• Implications of the isotope effects on the magnetization, magnetic torque and susceptibility