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Improvement in the Properties of Ag‐Doped YBa 2 Cu 3 O 7–x Grain Boundary Josephson Junctions
Author(s) -
Bolaños G.,
Baca E.,
Osario J.,
Prieto P.
Publication year - 2000
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/1521-3951(200007)220:1<517::aid-pssb517>3.0.co;2-p
Subject(s) - materials science , josephson effect , doping , superconductivity , grain boundary , condensed matter physics , electrical resistivity and conductivity , high temperature superconductivity , microwave , sputtering , analytical chemistry (journal) , thin film , microstructure , optoelectronics , nanotechnology , composite material , electrical engineering , chemistry , physics , engineering , chromatography , quantum mechanics
Ag‐doped YBa 2 Cu 3 O 7– x (YBCO) thin films using 5 to 20 wt% Ag‐doped YBCO targets have been grown by a dc sputtering technique on SrTiO 3 bicrystals. Critical currents of 4 to 5 × 10 6 A/cm 2 at 77 K were measured in YBCO films doped with 5 wt% Ag which has been found to be higher than the value of 1 × 10 6 A/cm 2 measured in undoped samples. The normal resistivity decreases by a doping of 5 wt% Ag and increases for higher Ag concentrations. The critical temperature, T c , of the Ag‐YBCO films remained unchanged at 92 K as in the undoped YBCO samples. An I c R n product of 170 μV at 77 K was found in Grain Boundary Josephson junctions (GBJJs) with 5 wt% Ag, compared with the value of 100 μV measured in undoped samples at the same temperature. Current–voltage characteristics were measured in GBJJs, showing Shapiro steps under microwave radiation and Fraunhofer patterns with an external magnetic field. The improvement in the normal and superconducting properties of Ag‐doped YBCO films has been interpreted using the De Gennes model to establish that YBCO containing metallic Ag addition shows a superconductor–normalmetal–superconductor (S–N–S) behavior, thereby the Ag‐doping enhances the weak link behavior and is, therefore, appropriate for electronic applications.