Degenerate ground state and anomalous flux hysteresis in an YBa2Cu3O7 grain boundary rf SQUID

Gardiner, C.H., Lee, R.A.M., Gallop, J.C., Tzalenchuk, A.Y., Macfarlane, J.C. and Hao, L. (2004) Degenerate ground state and anomalous flux hysteresis in an YBa2Cu3O7 grain boundary rf SQUID. Superconductor Science and Technology, 17(5), pp. 234-240. (doi:10.1088/0953-2048/17/5/028)

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Abstract

We report measurements of the flux hysteresis curves and trapped flux distribution in an YBa2Cu3O7 rf SQUID containing two closely spaced grain boundary Josephson junctions in parallel. Broadening of the flux distribution from T = 15 K to 30 K is followed by a bifurcation at T = 35 K which corresponds to a degenerate ground state. Above T ≈ 40 K the bifurcation disappears, the flux distribution narrows significantly and small secondary loops appear in the hysteresis curves. This behaviour can be modelled qualitatively if we assume a temperature dependent second harmonic term in the current–phase relationship of the junctions.

Item Type:Articles
Keywords:HTS SQUID.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Webster, Dr Carol
Authors: Gardiner, C.H., Lee, R.A.M., Gallop, J.C., Tzalenchuk, A.Y., Macfarlane, J.C., and Hao, L.
College/School:College of Science and Engineering > School of Computing Science
Journal Name:Superconductor Science and Technology
Publisher:IOP Publishing
ISSN:0953-2048
ISSN (Online):1361-6668
Published Online:19 March 2004

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