Superconducting micronets: The Wheatstone bridge

Journal Article · Mon May 01 04:00:00 EDT 1995 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.51.11739· OSTI ID:44539

Ammann, C; Erdoes, P ^[1]; Haley, S B ^[2]

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1. Institute of Theoretical Physics, University of Lausanne, CH-1015 Lausanne (Switzerland)
2. Department of Electrical and Computer Engineering, University of California, Davis, California 95616 (United States)

Using the Ginzburg-Landau theory, a particular superconducting (sc) micronet, called the Wheatstone bridge, is studied. This planar micronet is made of two nodes connected by three thin sc wires. A magnetic field is applied perpendicularly to its plane. The sc-normal second-order phase transition is characterized by only two configurations of the order parameter: {ital cphi}{sub {ital A}}={ital cphi}{sub {ital B}} and {ital cphi}{sub {ital A}}={minus}{ital cphi}{sub {ital B}}, where {ital cphi}{sub {ital A}} and {ital cphi}{sub {ital B}} are the order parameters at the nodes. For temperatures near {ital T}{sub {ital c}}, we show that only the {ital cphi}{sub {ital A}}={ital cphi}{sub {ital B}} configuration is admissible for fluxes near {Phi}={ital n}{Phi}{sub 0}, where {ital n} is an integer and {Phi}{sub 0} is the flux quantum. Finally, the exact solution of the nonlinear Ginzburg-Landau equations for one-dimensional systems is numerically fitted to the boundary conditions of the Wheatstone bridge for the two configurations {ital cphi}{sub {ital A}}={ital cphi}{sub {ital B}} and {ital cphi}{sub {ital A}}={minus}{phi}{sub {ital B}}. Graphs of the Gibbs energy and of the spontaneous supercurrent, which for these two configurations is always a screening supercurrent, are given as functions of the total flux. A discontinuous transition between configurations occurs as a function of the flux.

• OSTI ID: 44539
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 17 Vol. 51; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ELECTRIC BRIDGES
GINZBURG-LANDAU THEORY
MAGNETIC FIELDS
ONE-DIMENSIONAL CALCULATIONS
ORDER PARAMETERS
PHASE TRANSFORMATIONS
SUPERCONDUCTORS
TEMPERATURE DEPENDENCE