Title :
Linewidth of Josephson oscillations in YBa/sub 2/Cu/sub 3/O/sub 7-x/ grain-boundary junctions
Author :
Divin, Y.Y. ; Mygind, J. ; Pedersen, N.F. ; Chaudhari, P.
Author_Institution :
Tech. Univ. of Denmark, Lyngby, Denmark
fDate :
3/1/1993 12:00:00 AM
Abstract :
The AC Josephson effect in YBa/sub 2/Cu/sub 3/O/sub 7-x/ grain-boundary junctions (GBJs) was studied in the temperature range from 4 K to 90 K. The temperature dependence of the linewidth of millimeter-wave Josephson oscillations was measured, and it is shown that the derived effective noise temperature of GBJ might be as low as the physical temperature in the temperature range investigated. This makes it possible to use the resistively shunted junction (RSJ) model with thermal fluctuations to get a limiting performance of high-T/sub c/ devices utilizing the AC Josephson effect. The lowest value of the linewidth of 72 GHz Josephson oscillations observed at 77 K was equal to 380 MHz, which demonstrates the applicability of GBJ, particularly in the field of radiation spectroscopy, even at liquid nitrogen temperatures.<>
Keywords :
Josephson effect; barium compounds; fluctuations in superconductors; grain boundaries; high-frequency effects; high-temperature superconductors; spectral line breadth; superconducting junction devices; yttrium compounds; 4 to 90 K; 72 GHz; 77 K; AC Josephson effect; Josephson oscillation linewidth; RSJ model; YBa/sub 2/Cu/sub 3/O/sub 7-x/ grain boundary junctions; effective noise temperature; high temperature effect; liquid N/sub 2/ temperature; millimeter wave oscillations; radiation spectroscopy; resistively shunted junction model; temperature dependence; thermal fluctuations; Circuit analysis; Coupling circuits; Critical current; Frequency estimation; Impedance measurement; Josephson effect; Josephson junctions; Nitrogen; Temperature sensors; Voltage fluctuations;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
