Controlling superconducting spin flow with spin-flip immunity using a single homogeneous ferromagnet

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Electron spin transport is hindered by Joule heating and spin-flip scattering, limiting decay lengths.
• Dissipationless spin currents are known with superconducting contacts but require complex magnetic multilayers or specific materials.
• The decay behavior of spin supercurrents under spin-flip scattering remains largely unexplored.

Purpose of the Study:

• To develop a novel method for generating spin supercurrents using a single homogeneous magnetic element.
• To investigate the spatial decay characteristics of spin supercurrents generated via this new method.
• To explore the existence and nature of superconductivity-mediated torques in the absence of magnetic inhomogeneities.

Main Methods:

• Utilized a single homogeneous magnetic element in conjunction with superconducting contacts.
• Investigated spin supercurrent generation and propagation.
• Analyzed the response of spin supercurrent polarization components to changes in superconducting phase difference.

Main Results:

• Successfully generated a spin supercurrent that does not exhibit spatial decay, unlike conventional spin currents.
• Demonstrated a superconductivity-mediated torque without relying on magnetic inhomogeneities.
• Observed distinct responses of different spin supercurrent polarization components to superconducting phase shifts.

Conclusions:

• A new, robust method for generating dissipationless spin supercurrents has been established using simple magnetic elements.
• The findings reveal a fundamental difference in how spin supercurrents interact with superconducting phase, enabling independent control of spin and charge flow.
• Superconductors offer significant advantages for advancing spintronics technologies by enabling efficient and tunable spin transport.