Josephson behaviour and flux penetration effects in YBCO double tilt-angle step-edge junctions

Author

Foley, C.P. ; Sloggett, G.J. ; Muller, K.-H. ; Lam, S. ; Savvides, N. ; Katsaros, A. ; Matthews, D.N.

Author_Institution

Div. of Appl. Phys., CSIRO, Lindfield, NSW, Australia

Volume

5

Issue

2

fYear

1995

fDate

6/1/1995 12:00:00 AM

Firstpage

2805

Lastpage

2808

Abstract

YBCO thin-film step-edge junctions have been prepared whose characteristics show features corresponding to the two tilt-angle grain-boundary junctions formed at the step. The I-V characteristics of these junctions are fitted to high accuracy by a model consisting of two noisy resistively-shunted Josephson junctions. In applied magnetic fields up to a few hundred microtesla, both junction critical currents show reversible flux modulation, in one case indicating excellent uniformity of the critical current distribution along the step. In stronger magnetic fields, the junction critical current modulation shows evidence of flux penetration into the film, i.e. the mixed state. Taking demagnetising effects into account the lower critical field of YBCO at 77 K, /spl mu//sub 0/H/sub e1,e/, is found to be 12 mT.<>

Keywords

Josephson effect; barium compounds; critical currents; high-temperature superconductors; mixed state; superconducting critical field; superconducting device testing; superconducting junction devices; yttrium compounds; 12 mT; 77 K; I-V characteristics; Josephson behaviour; MgO; YBCO thin-film step-edge junctions; YBa/sub 2/Cu/sub 3/O/sub 7/; applied magnetic fields; critical current distribution; critical currents; demagnetising effects; flux penetration effects; junction critical current modulation; lower critical field; mixed state; noisy resistively-shunted Josephson junctions; reversible flux modulation; two tilt-angle grain-boundary junctions; Australia; Critical current; Grain boundaries; Josephson junctions; Magnetic fields; Magnetic modulators; Physics; Substrates; Transistors; Yttrium barium copper oxide;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.403174

Filename

403174