Vortex solid phase with frozen undulations in superconducting Josephson-junction arrays in external magnetic fields

TL;DR

This paper theoretically discovers a vortex solid with frozen undulations in anisotropic Josephson-junction arrays under magnetic fields, revealing complex metastable states and anisotropic sliding behavior.

Contribution

It introduces a new vortex solid phase with self-generated randomness and analyzes its metastable states and anisotropic dynamics.

Findings

Vortices form stripe patterns aligned with weaker coupling directions.

A continuous band of metastable states with transverse undulations exists.

The vortex solid can slide freely along stronger coupling but is jammed along weaker coupling.

Abstract

A vortex solid with self-generated randomness is found theoretically in a frustrated Josephson junction array (JJA) under external magnetic field with anisotropic couplings. Vorticies induced by external magnetic field develop stripes parallel to the direction of weaker coupling. It is shown analytically that there is a continuous, gapless band of metastable states in which stripes are deformed randomly by transverse undulation. The vortex solid with the frozen undulation in a metastable state freely slides along the direction of stronger coupling, thereby destroying ordering of phases even at zero temperature, but is jammed along the direction of weaker coupling.