Title :
Investigation of YBa/sub 2/Cu/sub 3/O/sub 7/ Josephson junctions on MgO bicrystal substrates
Author :
Vonderbeck, L. ; Copetti, C.A. ; Klushin, A.M. ; Kunkel, G. ; Siegel, M. ; Sodtke, E. ; Schubert, J. ; Zander, W.
Author_Institution :
Inst. fur Schicht- und Ionentech., Forschungszentrum Julich GmbH, Germany
fDate :
6/1/1995 12:00:00 AM
Abstract :
We report on the characterization of the dynamic (ac) properties of YBa/sub 2/Cu/sub 3/O/sub 7/ Josephson junctions on MgO bicrystal substrates with 24/spl deg/ angle. Shapiro steps have been measured in the frequency range 80-95 GHz. Measured current-voltage characteristics, as well as the dependence of Shapiro step height on microwave power, were compared to numerical simulations within the RSJ model including thermal noise. At 77 K, the junctions showed ideal RSJ behavior. The occurrence of half-integer Shapiro steps at lower temperatures could be explained by an inhomogeneous critical current density of the junctions yielding a dc SQUID-like behavior. A nonsinusoidal current-phase relation could be ruled out because of the periodicity of the half-integer steps.<>
Keywords :
Josephson effect; SQUIDs; barium compounds; critical current density (superconductivity); millimetre wave devices; superconducting device noise; superconducting device testing; superconducting microwave devices; thermal noise; yttrium compounds; 77 K; 80 to 95 GHz; Josephson junctions; MgO; RSJ model; Shapiro steps; YBa/sub 2/Cu/sub 3/O/sub 7/-MgO; bicrystal substrates; current-voltage characteristics; dc SQUID-like behavior; dynamic properties; half-integer step periodicity; inhomogeneous critical current density; microwave power; resistively shunted junction; thermal noise; Current measurement; Current-voltage characteristics; Frequency measurement; Josephson junctions; Microwave measurements; Noise measurement; Noise shaping; Numerical simulation; Power measurement; Temperature;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
