Dynamics of Two Ferromagnetic Insulators Coupled by Superconducting Spin Current

Area of Science:

• Condensed Matter Physics
• Spintronics
• Superconductivity

Background:

• Superconductors interfaced with ferromagnets can exhibit unique spin-related phenomena.
• The magnetic proximity effect induces spin correlations within the superconductor.
• Understanding spin supercurrents is crucial for advanced spintronic devices.

Purpose of the Study:

• To investigate the behavior of spin supercurrents in superconductor-ferromagnet heterostructures.
• To determine the current-phase relation analog for spin supercurrents.
• To explore the impact of spin supercurrents on dynamic magnetization phenomena.

Main Methods:

• Theoretical analysis of odd-frequency spin correlations.
• Modeling of Josephson-type weak links for spin supercurrents.
• Investigation of magnetic hysteresis and ferromagnetic resonance response.

Main Results:

• A coherent equilibrium spin supercurrent can be maintained.
• The superconductor acts as a weak link for spin supercurrents in the absence of intrinsic magnetization.
• Spin supercurrents influence nonequilibrium magnetization dynamics through a competition between static exchange and dynamic spin pumping.

Conclusions:

• Spin supercurrents significantly affect the dynamic response of ferromagnet-superconductor systems.
• The interplay between spin supercurrents and magnetization dynamics dictates phenomena like mode locking or avoided crossings.
• Experimental probes of dynamic magnetization can reveal the properties of induced spin supercurrents.