Superconducting micronets: The Wheatstone bridge

Christine Ammann; Paul Erdös; Stephen B. Haley

doi:10.1103/PhysRevB.51.11739

← Back to search

Superconducting micronets: The Wheatstone bridge

Christine Ammann, Paul Erdös, Stephen B. Haley

DOI 10.1103/PhysRevB.51.11739 · Physical Review B

T1

Active bibliographic source — not scientific approval

Bibliographic access preserves source history; it does not approve extracted materials or validate reported claims. Review warnings on each occurrence separately.

Abstract

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: cphiA=cphiB and cphiA=-cphiB, where cphiA and cphiB are the order parameters at the nodes. For temperatures near Tc, we show that only the cphiA=cphiB configuration is admissible for fluxes near Φ=nΦ0, where n is an integer and Φ0 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 cphiA=cphiB and cphiA=-φB. 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.