Title :
Fabrication of RS flip-flops using Y-Ba-Cu-O ramp-edge junctions and their operation
Author :
Park, J.H. ; Kim, J.H. ; Sung, G.Y. ; Kim, C.H. ; Jung, K.R. ; Kang, J.H. ; Hahn, T.S.
Author_Institution :
Korea Inst. of Sci. & Technol., Seoul, South Korea
fDate :
3/1/2001 12:00:00 AM
Abstract :
We fabricated single flux quantum RS flip-flop circuits by using ramp-edge Josephson junctions and tested their performance. The junctions were constructed with two Y1Ba2Cu3 O7-x (YBCO) electrodes and a barrier layer. As barrier materials we used cobalt-doped YBCO. To insulate between YBCO layers we used Sr2AlTaO6 (SAT) thin films. We also fabricated RS flip-flop circuits by using YBCO ground planes to reduce the inductance of YBCO film. The fabricated Josephson junctions showed typical RSJ-like current-voltage (I-V) characteristics above 50 K. We could successfully demonstrate the correct operation of the RS flip-flop circuits at the temperatures near 50 K. We used a computer controlled digital measurement set-up to test the circuits. The RS flip-flop circuit fabricated on a ground plane showed more definite set and reset states on the voltage-flux (V-φ) modulation curves of the read SQUID than those of the circuit made without ground plane. This may be attributed to the shielding effect by a YBCO ground plane
Keywords :
barium compounds; flip-flops; high-temperature superconductors; superconducting logic circuits; yttrium compounds; 50 K; RSJ model; SAT insulating thin film; SFQ RS flip-flop circuit; SQUID; Sr2AlTaO6; Y1Ba2Cu3O7; Y1Ba2Cu3O7:Co; YBCO electrode; YBCO ground plane; cobalt-doped YBCO barrier layer; computer controlled digital measurement; current-voltage characteristics; fabrication; inductance; ramp-edge Josephson junction; voltage-flux modulation; Circuit testing; Electrodes; Fabrication; Flip-flops; Inductance; Insulation; Josephson junctions; Strontium; Thin film circuits; Yttrium barium copper oxide;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
