Influence of the passive region on Zero Field Steps for window Josephson junctions

TL;DR

This study investigates how the passive region's electromagnetic properties affect fluxon dynamics and zero field steps in window Josephson junctions through numerical and analytical methods.

Contribution

It provides new formulas for the limiting voltage of zero field steps considering passive region effects and analyzes different solution types based on inductance and capacitance.

Findings

Fluxon velocity adapts to passive region velocity when different from Swihart velocity.

Formulas for zero field step voltages are derived.

Different solution behaviors emerge with large inductance and capacitance.

Abstract

We present a numerical and analytic study of the influence of the passive region on fluxon dynamics in a window junction. We examine the effect of the extension of the passive region and its electromagnetic characteristics, its surface inductance and capacitance. When the velocity in the passive region $v_{I}$ is equal to the Swihart velocity (1) a one dimensional model describes well the operation of the device. When $v_{I}$ is different from 1, the fluxon adapts its velocity to $v_{I}$. In both cases we give simple formulas for the position of the limiting voltage of the zero field steps. Large values of inductance and capacitance lead to different types of solutions which are analyzed.