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© The American Physical Society. This work was supported by the CICYT Grant No. BMF2001-1419, the ESF Network “Phi-shift,” the project DG236RIC “NDA” and the TRN “DeQUACS.”, We have studied the electromagnetic parameters of YBa2Cu3O7 Josephson junctions fabricated on bicrystalline substrates with different angles tilted around the [100] and [001] axis. Changing a technological parameter such as the junction width permits change to the resonant frequency of the barrier cavity. This change in the resonance frequency allows one to determine a frequency dependent dispersion relation of the dielectric constant epsilon(omega). We have explored the proximity to a resonance in the dielectric response and analyzed its resonance frequency and damping constant. In terms of a RLC circuital equivalence additional information on the inductive response is presented as a comparative study of junctions fabricated on substrates with different bicrystalline misorientations., CICYT, ESF Network “Phi-shift”, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© The American Physical Society. The authors would like to thank C.A.I de Implantación Iónica from the Universidad Complutense in Madrid for assistance with lithography facilities. Financial support from CICYT Grant No. BMF2001-1419 is acknowledged. This work has been partially supported by the ESF Network “Pishift,” the project DG236RIC “NDA,” the TRN “De-QUACS,” and the regional project L.R. N.5 “Proprietà di trasporto e di interfaccia in giunzioni Josephson HTcsu scala submicrometrica.”, The electromagnetic parameters of YBa2Cu3O7-x (YBCO) grain boundary Josephson junctions (JJs) fabricated on four different tilt bicrystal geometries: 12degrees [001] asymmetric, 24degrees [001] symmetric, 24degrees [001] asymmetric, and 45degrees [100] asymmetric, have been studied. While the Swihart velocity ((c) over bar) is slightly affected by the nature of the barrier and mainly fixed by the junction width, a notable influence of the barrier structure, of the geometry of the bicrystal substrate, on the relative dielectric constant to the barrier thickness ratio (epsilon/t) values has been found. Interesting barrier information can be deduced from the study of the dependence of the junction capacitance on the junction resistance. We have observed that the capacitance values deduced by means of Fiske steps in YBCO 24degrees [001] symmetric and 45degrees [100] asymmetric JJs scales with junction resistance in the opposite direction. This result could reveal the presence of a tunnel barrier in the YBCO 45degrees [100] asymmetric JJs. On the other hand, different capacitance values have been obtained by means of Fiske steps and hysteresis observed in the current-voltage characteristics in 45degrees [100] asymmetric JJs. An interpretation of this result can be made taking into account the contribution of the depleted YBCO layers close to the crystallographic grain boundary., CICYT, ESF Network “Pishift”, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub