A comparative analysis of grain boundary junctions modified by oxygen annealings and irradiation
Centro de Estudios Superiores Felipe II c/Capitán 39, 28300 Aranjuez,
2 Departamento de Física Aplicada III, Facultad de Ciencias Físicas Universidad Complutense, 28040 Madrid, Spain
Accepted: 23 February 2001
In order to bring new data about the physics of the microscopic (YBCO) grain boundary mechanism, we have used two different ways to induce modifications in the oxygen sublattice of grain boundary Josephson junctions (GBJs): annealings and irradiation with helium at 80 of both electrodes and barrier. We present a comparative study in terms of the main electromagnetic and transport parameters between irradiated and oxygen-deficient junctions with the same critical temperature. In irradiated junctions the coupling energy of the barrier can be enhanced when the superconducting properties of the electrodes are not severely degraded. The modification of the barrier properties depends on the dose and on the particular distribution of the critical current inside the barrier. Changes of the ratio of the relative dielectric constant to the barrier thickness () upon irradiation are mainly due to changes in ε, and progress in the same direction as the normal resistance (). On the other hand, a reduction of the oxygen content by annealing of YBCO thin film always causes a degradation of the barrier coupling energy. increases along with both ε and t.
PACS: 74.50.+r – Proximity effects, weak links, tunneling phenomena, and Josephson effects
© EDP Sciences, 2001