Subgap modes in two-dimensional magnetic Josephson junctions

We consider two-dimensional superconductor/ferromagnet/superconductor junctions, and we investigate the subgap modes along the junction interface. The subgap modes exhibit characteristics similar to the Yu-Shiba-Rusinov states that originate from the interplay between superconductivity and ferromagnetism in the magnetic junction. The dispersion relation of the subgap modes shows qualitatively different profiles depending on the transport state (metallic, half-metallic, or insulating) of the ferromagnet. As the spin splitting in the ferromagnet is increased, the subgap modes bring about a 0-pi transition in the Josephson current across the junction, with the Josephson current density depending strongly on the momentum along the junction interface (i.e., the direction of the incident current). For clean superconductor-ferromagnet interfaces (i.e., strong coupling between superconductors and ferromagnet), the subgap modes develop flat quasiparticle bands that allow us to engineer the wave functions of the subgap modes along an inhomogeneous magnetic junction.

Automated summary

We study subgap modes in two-dimensional superconductor/ferromagnet/superconductor junctions and find that these modes exhibit characteristics similar to Yu-Shiba-Rusinov states. The dispersion relation of the subgap modes shows different profiles depending on the transport state of the ferromagnet. Increasing spin splitting in the ferromagnet leads to a 0-pi transition in the Josephson current across the junction, with the Josephson current density strongly dependent on the momentum along the junction interface. Clean superconductor-ferromagnet interfaces allow for engineering the wave functions of the subgap modes along an inhomogeneous magnetic junction.