Row-switched states in two-dimensional underdamped Josephson junction arrays

TL;DR

This paper analytically investigates row-switched states in underdamped 2D Josephson junction arrays, revealing their stability conditions and spatial distributions under magnetic fields and DC currents, with results validated numerically.

Contribution

It provides a novel analytical framework for understanding and predicting the behavior and stability of row-switched states in Josephson arrays under external magnetic fields.

Findings

Analytical expressions for phase and current distributions in RS states.

Identification of parameter regions where RS states are stable.

Good agreement between analytical predictions and numerical simulations.

Abstract

When magnetic flux moves across layered or granular superconductor structures, the passage of vortices can take place along channels which develop finite voltage, while the rest of the material remains in the zero-voltage state. We present analytical studies of an example of such mixed dynamics: the row-switched (RS) states in underdamped two-dimensional Josephson arrays, driven by a uniform DC current under external magnetic field but neglecting self-fields. The governing equations are cast into a compact differential-algebraic system which describes the dynamics of an assembly of Josephson oscillators coupled through the mesh current. We carry out a formal perturbation expansion, and obtain the DC and AC spatial distributions of the junction phases and induced circulating currents. We also estimate the interval of the driving current in which a given RS state is stable. All these analytical predictions compare well with our numerics. We then combine these results to deduce the parameter region (in the damping coefficient versus magnetic field plane) where RS states can exist.