Stability of current-carrying states in Josephson-junction arrays.

Abstract

Analytic and numerical calculations are presented for current-carrying states in frustrated Josephson-junction arrays. In particular, we study a family of states which are a generalization of the ``staircase'' states proposed by Halsey. For the fully frustrated case, it is possible to obtain exact analytic solutions explicitly in terms of the net supercurrent orientation. We find states that carry currents up to critical values of ${\mathit{I}}_{\mathit{c}1}$ which are larger than the intrinsic critical currents ${\mathit{I}}_{\mathit{c}0}$ obtained previously by other authors. However, an analysis of the stability of these new states shows that they are unstable to fluctuations in the phases of the superconducting grains.