High T/sub c/ SNS step-edge junctions and SQUIDs by using; YBa/sub 2/Cu/sub 3/O/sub 7//CaRuO/sub 3/ double layer

Author

Soon-Gul Lee ; Keunseop Park ; Hyuk Chan Kwon ; Yong Ki Park ; Jong-Chul Park ; Doo-Sup Hwang

Author_Institution

Korea Res. Inst. of Standards & Sci., Taejon, South Korea

Volume

5

Issue

2

fYear

1995

fDate

6/1/1995 12:00:00 AM

Firstpage

2509

Lastpage

2512

Abstract

Superconductor-normal-superconductor (SNS) step-edge junction dc SQUIDs were fabricated from YBa/sub 2/Cu/sub 3/O/sub 7/ (YBCO) films with CaRuO/sub 3/ (CRO) on top as the normal metal. The films were made by pulsed laser deposition (PLD) and patterned by photolithography and ion milling. The junctions and SQUIDs had to be annealed in oxygen environment for a much longer period of time (5-48 hours) compared with standard YBCO film preparation (as deposited or 1 hour), indicating that the top CRO film blocks oxygen in and out of the YBCO film. Before annealing T/sub c/´s of CRO/YBCO double layers and junctions made from them were <70 X and <50 K, respectively, and increased to >88 K and >77 K, respectively after long time annealing. Current-voltage curves of the junctions showed well-behaved resistively-shunted-junction (RSJ) properties and the temperature dependence of the junction critical current was roughly linear. SQUIDs made of those junctions showed voltage modulation in response to applied fields at 77 K.<>

Keywords

SQUIDs; annealing; barium compounds; calcium compounds; critical currents; high-temperature superconductors; ion beam applications; photolithography; pulsed laser deposition; superconducting device testing; superconducting transition temperature; yttrium compounds; 5 to 48 hour; 77 to 88 K; O/sub 2/ environment; YBa/sub 2/Cu/sub 3/O/sub 7/-CaRuO/sub 3/; YBa/sub 2/Cu/sub 3/O/sub 7//CaRuO/sub 3/ double layer; critical current; current-voltage curves; high T/sub c/ SNS step-edge junctions; ion milling; long time annealing; photolithography; pulsed laser deposition; resistively-shunted-junction properties; superconductor-normal-superconductor step-edge junction DC SQUIDs; temperature dependence; transition temperature; voltage modulation; Annealing; Josephson junctions; Lithography; Milling; Optical pulses; Pulsed laser deposition; SQUIDs; Superconducting devices; Superconducting films; Yttrium barium copper oxide;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.403100

Filename

403100