Title :
Modulation of I-V characteristics of YBCO films and tunnel junctions under microwave irradiation and tunnel current injection
Author :
Qian Wang ; Kijin Lee ; Ienari Iguchi
Author_Institution :
Inst. of Mater. Sci., Tsukuba Univ., Ibaraki, Japan
fDate :
6/1/1995 12:00:00 AM
Abstract :
We present the measurements on the I-V characteristic modulation of YBCO films under microwave irradiation and tunnel current injection. In the case of tunnel current injection through a Pb(or Au)/MgO/YBCO junction, the critical current I/sub c/ of a YBCO film decreases drastically with the increase in tunnel current, and a normal state appears when the injection current reaches a certain value smaller than I/sub c/, leading to a current gain greater than one. The I-V characteristics of a YBCO film under both current injection and external microwave irradiation (fa=11 GHz) show strong modulation behavior. We find that the above modulation is mainly caused by the Cooper-pair breaking effect due to injected quasiparticles with energy greater than 2/spl Delta/ and not by heating.<>
Keywords :
Cooper pairs; Josephson effect; barium compounds; critical currents; high-temperature superconductors; superconducting junction devices; superconducting thin films; yttrium compounds; 11 GHz; Au-MgO-YBaCuO; Au/MgO/YBCO junction; Cooper-pair breaking; I-V characteristics; Pb-MgO-YBaCuO; Pb/MgO/YBCO junction; YBCO films; critical current; current gain; current injection; microwave irradiation; modulation; normal state; quasiparticles; tunnel junctions; Current measurement; Electrodes; Electromagnetic heating; Electromagnetic radiation; Gold; Phonons; Superconducting films; Superconducting materials; Superconducting microwave devices; Yttrium barium copper oxide;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
