Magnonic Shapiro step and chaotic behavior in magnonic Josephson junction

Esaki, Nanse; Nakata, Koki   ; 2 of others*

The Josephson effect exemplifies macroscopic phase coherence and manifests across diverse physical systems, from superconductors to ultracold atoms and magnetic materials. While Shapiro steps are a well-known hallmark in superconducting Josephson junctions, their magnonic counterparts have remained largely unexplored. Here, we present a theoretical study that maps the dynamics of a magnonic Josephson junction onto the resistively and capacitively shunted junction model for superconductors. Using analytical and numerical methods, we show that coherent magnons driven by a time-periodic magnetic field exhibit Shapiro step-like behavior. Notably, local damping stabilizes the magnonic Shapiro steps, whereas strong magnon-magnon interactions can induce chaotic dynamics. These findings are experimentally accessible at room temperature and open new avenues for controlling the nonlinear dynamics of macroscopic coherent magnons.