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Free keywords:
high-temperature superconductivity; two-component scenario
Abstract:
A variety of different experimental results show substantial
evidence that the order parameter in high-temperature
superconducting copper oxides is not of pure d-wave symmetry,
but that an s-wave component exists, which especially shows up
in experiments that test the c-axis properties. These findings
are modeled theoretically within a two-band model with
interband interactions, where the superconducting order
parameters in the two bands are allowed to differ in symmetry.
It is found that the coupling of order parameters with
different symmetries (s+d) leads to substantial enhancements of
the superconducting transition temperature T-c as compared to
order parameters with only s-wave symmetry. An additional
enhancement factor of T-c is obtained from the coupling of the
bands to the lattice where moderate couplings favor
superconductivity while too strong couplings lead to electron
(hole) localization and consequently suppress
superconductivity.
