Abstract:
In this work, the magnetic field penetration depth for high-Tc cuprate superconductors
is calculated using a recent Interlayer Pair Tunneling (ILPT) model proposed by
Chakravarty, Sudb0, Anderson, and Strong [1] to explain high temperature superconductivity.
This model involves a "hopping" of Cooper pairs between layers of the unit
cell which acts to amplify the pairing mechanism within the planes themselves. Recent
work has shown that this model can account reasonably well for the isotope effect and
the dependence of Tc on nonmagnetic in-plane impurities [2] , as well as the Knight shift
curves [3] and the presence of a magnetic peak in the neutron scattering intensity [4]. In
the latter case, Yin et al. emphasize that the pair tunneling must be the dominant pairing
mechanism in the high-Tc cuprates in order to capture the features found in experiments.
The goal of this work is to determine whether or not the ILPT model can account for
the experimental observations of the magnetic field penetration depth in YBa2Cu307_a7.
Calculations are performed in the weak and strong coupling limits, and the efi"ects of both
small and large strengths of interlayer pair tunneling are investigated. Furthermore, as a
follow up to the penetration depth calculations, both the neutron scattering intensity and
the Knight shift are calculated within the ILPT formalism. The aim is to determine if the
ILPT model can yield results consistent with experiments performed for these properties.
The results for all three thermodynamic properties considered are not consistent with
the notion that the interlayer pair tunneling must be the dominate pairing mechanism
in these high-Tc cuprate superconductors. Instead, it is found that reasonable agreement
with experiments is obtained for small strengths of pair tunneling, and that large pair
tunneling yields results which do not resemble those of the experiments.
