Semicircular Josephson junction embedded in a magnetic field

Abstract

A semicircular geometry is proposed for overlap Josephson junctions for experimental realization. Analytical and numerical studies on semicircular junctions show that an external static magnetic field applied parallel to the dielectric barrier interacts through the interior of the junction and produces a tilted potential which pushes out trapped fluxons from the interior of the junction, and a flux-free state exists in the junction in the absence of an external bias. Due to the semicircular shape, the effective field at the ends of the junction has opposite polarities which support penetration of opposite polarity fluxons into the junction in the presence of a forward-biased dc current. When the direction of the dc current is reversed, flux penetration is not possible and a flux-free state exists in the junction. Thus this geometry can be used in implementing a fluxon-based diode. The rectification properties of the junction are demonstrated using square-wave signals and sinusoidal ac signals. In the forward-biased state, fluxons and antifluxons enter the junction and move in opposite directions. Using this property, we propose and demonstrate a bidirectional flux-flow oscillator.