Towards weakening of the Coulomb blockade in artificially prepared clusters of superconducting grains

The relative role of dipole-dipole interactions between induced polarization moments in the total charge balance of a model system of two clusters (each cluster contains N superconducting grains) is analyzed. It is found that, due to its orientational nature, the dipole energy between clusters may overcome the direct Coulomb coupling between grains (within a single cluster). To verify the model predictions experimentally, specially prepared clusters with markedly distinctive grain-grain (εc) and cluster-cluster (εd) dielectric properties are needed. More specifically, clusters of Al-based superconducting grains embedded into SrTiO3 dielectric matrix (with εc ≃ 104) and separated by a dielectric layer of Al2O3 (with εd ≃ 10) would result in a noticeable decrease of the total charging energy of the system.