Transport processes and noise in YBa2Cu3O7−δ grain boundary junctions

In the high temperature superconductors the weak link nature of extended defects as grain boundaries is responsible for the deterioration of the superconducting transport properties. From the study of individual grain boundaries in thin-film bicrystals of YBa2Cu3O7−δ general relations describing the superconducting transport and noise characteristics of grain boundaries in the high temperature superconductors were found. Firstly, the critical current density Jgbc decreases as the misorientation angle between the adjoining grains increases. Secondly, the Jgbc ϱN products, where ϱN is the normal resistance times unit area of the grain boundaries, scale proportional to about (1/ϱN)q with q ranging between 1 and 1.5. Thirdly, all grain boundaries show large amounts of low frequency 1/f noise. The transport and noise characteristics can be explained by a junction model which is based on an insulating layer at the grain boundary interface containing a large number of localized defect states.

[1]  Low-frequency noise and discrete charge trapping in small-area tunnel junction dc SQUID's , 1986 .

[2]  D. Dimos,et al.  Superconducting transport properties of grain boundaries in YBa2Cu3O7 bicrystals. , 1990, Physical review. B, Condensed matter.

[3]  R. Buhrman,et al.  Characterization of individual electron traps in amorphous Si by telegraph noise spectroscopy , 1986 .

[4]  D. Dimos,et al.  Thermally activated phase slippage in high-Tc grain-boundary Josephson junctions. , 1990, Physical review letters.

[5]  Valles,et al.  Reproducible tunneling data on chemically etched single crystals of YBa2Cu3O7. , 1989, Physical review letters.

[6]  Beasley,et al.  Transport processes via localized states in thin a-Si tunnel barriers. , 1985, Physical review letters.

[7]  D. Dimos,et al.  Orientation dependence of grain-boundary critical currents in YBa2Cu3O7- delta bicrystals. , 1988, Physical review letters.

[8]  McGuire,et al.  Critical currents in , 1988, Physical review letters.

[9]  Gross,et al.  Scaling behavior in electrical transport across grain boundaries in YBa2Cu3O7- delta superconductors. , 1990, Physical review. B, Condensed matter.

[10]  P. D. Gennes,et al.  Superconductivity of metals and alloys , 1966 .

[11]  J. Halbritter.  On resonant tunneling , 1982 .

[12]  R. Gruehn,et al.  Mechanism of the transition from orthorhombic to tetragonal YBa2Cu3O7−x. Investigation of a reversible topotactic reaction in the electron microscope , 1989 .

[13]  M. Kawasaki,et al.  Noise characteristics of single grain boundary junction DC SQUIDs in Y1Ba2Cu3O7−δ films , 1990 .

[14]  J. Halbritter.  Potential barrier model incorporating localized states explaining tunnel anomalies , 1985 .

[15]  Chi,et al.  Direct measurement of the superconducting properties of single grain boundaries in Y1Ba2Cu3O7- delta. , 1988, Physical review letters.

[16]  D. Dimos,et al.  Spatially Resolved Observation of Supercurrents Across Grain Boundaries in YBaCuO Films , 1989, Science.

[17]  J. Halbritter.  Changes of superconducting interaction in interfaces , 1976 .

[18]  D. Mccumber.  Effect of ac Impedance on dc Voltage‐Current Characteristics of Superconductor Weak‐Link Junctions , 1968 .

[19]  Vinay Ambegaokar,et al.  Tunneling between superconductors , 1963 .

[20]  A. Barone,et al.  Physics and Applications of the Josephson Effect , 1982 .

[21]  W. C. Stewart,et al.  CURRENT‐VOLTAGE CHARACTERISTICS OF JOSEPHSON JUNCTIONS , 1968 .

[22]  J. Halbritter.  PERCOLATION IN SUPERCONDUCTING CUPRATES: RESISTIVITY AND CRITICAL CURRENTS , 1989 .

[23]  M. Kawasaki,et al.  Low noise YBa2Cu3O7−δ grain boundary junction dc SQUIDs , 1990 .

[24]  Jian Li,et al.  Growth of YBa2Cu3O7 thin films on MgO: The effect of substrate preparation , 1990 .

[25]  Robert A. Buhrman,et al.  Composition of 1/f noise in metal-insulator-metal tunnel junctions , 1984 .

[26]  John Clarke,et al.  dc SQUID: Noise and optimization , 1977 .

[27]  P. J. Restle,et al.  Non-Gaussian effects in 1/f noise in small silicon-on-sapphire resistors. , 1985, Physical review. B, Condensed matter.

[28]  D. K. Lathrop,et al.  GROWTH AND PROPERTIES OF YBA2CU3O7 THIN FILMS ON VICINAL AND POLYCRYSTALLINE MGO SUBSTRATES , 1990 .

[29]  Vinay Ambegaokar,et al.  VOLTAGE DUE TO THERMAL NOISE IN THE dc JOSEPHSON EFFECT. , 1969 .

[30]  D. K. Lathrop,et al.  Scaling behavior of YBa2Cu3O7−δ thin‐film weak links , 1990 .