Experiments and Simulations of Electrical Pulse Modulation of Y-Ba-Cu-O Thin Films

Carlo WILLIAMS, Guillaume SABOURET, Roman SOBOLEWSKI

Summary :

We report our studies on electrical current pulse perturbation of superconducting YBa₂Cu₃O_7-x (YBCO) epitaxial thin films. When a current pulse is applied to a YBCO microbridge, a voltage develops across it that depends on the amplitude of the input current pulse. For a total current (input current pulse plus the dc bias) that is lower than the critical current I_c, an inductive voltage response is observed. When the total current exceeds I_c, a resistive response is generated and is observed after a certain delay time t_d. The origin of the resistive response was analyzed using the Geier and Schon model, which is based on the time-dependent Ginzburg-Landau equation. Our experimental samples consisted of 200-nm-thick epitaxial YBCO films, patterned into coplanar-strip (CPS) transmission lines, containing either two-microbridge or single-microbridge test structures. For the two-microbridge samples, a train of 100-fs-duration optical pulses was used to excite the larger microbridge and generate 2-ps-duration electrical pulses, which were then applied to perturb the smaller microbridge, which was independently biased in the superconducting state. In this case, an electro-optic sampling system was used to measure the YBCO kinetic-inductive voltage responses with the picosecond time resolution. For the single-microbridge structures, an electronic pulse generator was employed to supply the input current pulse, and a 14-GHz sampling oscilloscope was used to monitor the microbridge responses. The latter signals were in very good agreement with the model of Geier and Schon, assuming that the quasiparticle dynamics process that resulted from the nanosecond-wide current excitation was bolometric and followed the phonon escape time τ_es.

• Publication: IEICE TRANSACTIONS on Electronics Vol.E85-C No.3 pp.733-737
• Publication Date: 2002/03/01
• Type of Manuscript: Special Section PAPER (Special Issue on Superconductive Electronics)
• Category: Mixers and Detectors

Authors

Carlo WILLIAMS
Guillaume SABOURET
Roman SOBOLEWSKI

Keyword

Y-Ba-Cu-O thin film,  Y-Ba-Cu-O microbridge,  kinetic-inductive voltage response,  supercritical current modulation,  superconductive-resistive transition