Abstract
It is shown that bulk superconductivity of a three-dimensional granular metal can become unstable with respect to the diverging zero-point phase fluctuations which result from grain charging. A model of Josephson-coupled superconducting grains is used to calculate the effect of charging energy on the average order parameter at . In the mean-field approximation this system exhibits a second-order transition to normal state at a certain critical value of the ratio of the Josephson-coupling constant to the charging energy. The self-consistent harmonic approximation is shown to yield a spurious first-order transition.
- Received 23 August 1979
DOI:https://doi.org/10.1103/PhysRevB.22.459
©1980 American Physical Society