Microwave induced tunable subharmonic steps in superconductor-ferromagnet-superconductor Josephson junction

TL;DR

This paper explores how microwave radiation can induce and tune subharmonic steps in superconductor-ferromagnet-superconductor Josephson junctions, revealing a devil's staircase pattern influenced by various external parameters.

Contribution

It demonstrates the tunability of subharmonic steps and their widths via external magnetic field frequency, energy ratios, damping, and junction size in these junctions.

Findings

Subharmonic current steps form a devil's staircase pattern.

Step width is maximized at ferromagnetic resonance.

Step structure and widths can be tuned by external parameters.

Abstract

We investigate the coupling between ferromagnet and superconducting phase dynamics in superconductor-ferromagnet-superconductor Josephson junction. The current-voltage characteristics of the junction demonstrate a pattern of subharmonic current steps which forms a devil's staircase structure. We show that a width of the steps becomes maximal at ferromagnetic resonance. Moreover, we demonstrate that the structure of the steps and their widths can be tuned by changing the frequency of the external magnetic field, ratio of Josephson to magnetic energy, Gilbert damping and the junction size.