Coupled Superconducting Phase and Ferromagnetic Order Parameter Dynamics

TL;DR

This paper demonstrates the detection of spin-wave resonances in ferromagnetic Josephson junctions through direct coupling between magnetic order and supercurrent, revealing new insights into their dynamic interactions.

Contribution

It introduces a novel method to observe spin-wave resonances via Josephson effect coupling in ferromagnetic barriers, using a minimal number of atoms.

Findings

Detection of spin-wave resonances in ferromagnetic Josephson junctions.

Observation of resonance-induced features in current-voltage characteristics.

Identification of the magnetic layer as a dynamic phase modulator.

Abstract

Via a direct coupling between the magnetic order parameter and the singlet Josephson supercurrent, we detect spin-wave resonances, and their dispersion, in ferromagnetic Josephson junctions in which the usual insulating or metallic barrier is replaced with a weak ferromagnet. The coupling arises within the Fraunhofer interferential description of the Josephson effect, because the magnetic layer acts as a time dependent phase plate. A spin-wave resonance at a frequency ws implies a dissipation that is reflected as a depression in the current-voltage curve of the Josephson junction when hbar ws = 2eV. We have thereby performed a resonance experiment on only 10^7 Ni atoms.