Superconducting spintronic heat engine

Area of Science:

• Condensed Matter Physics
• Quantum Engineering
• Materials Science

Background:

• Heat engines are crucial for energy conversion, with thermoelectricity offering a pathway for electrical heat engines.
• Superconducting spintronic devices exhibit strong thermoelectric effects at cryogenic temperatures, outperforming conventional technologies.
• Existing thermoelectric devices face limitations at very low temperatures, necessitating new approaches.

Purpose of the Study:

• To realize and characterize a superconducting spintronic heat engine.
• To investigate the efficiency and thermoelectric properties of a ferromagnetic insulator/superconductor/insulator/ferromagnet tunnel junction.
• To demonstrate the potential for thermoelectric memory applications.

Main Methods:

• Fabrication of a ferromagnetic insulator/superconductor/insulator/ferromagnet tunnel junction (EuS/Al/AlOx/Co).
• Quantification of engine efficiency across a temperature range (25 mK to 800 mK) and varying load resistances.
• Measurement of thermoelectric voltage with different magnetic layer orientations.

Main Results:

• Successful realization of a superconducting spintronic heat engine.
• Demonstrated tunable thermoelectric voltage by altering ferromagnetic layer alignment (parallel vs. anti-parallel).
• Achieved control over the Seebeck coefficient sign and magnitude, enabling a thermoelectric memory cell function.

Conclusions:

• The superconducting spintronic heat engine operates effectively at cryogenic temperatures.
• The device offers a novel approach to thermoelectric energy conversion and memory applications.
• A theoretical model was developed to explain experimental findings and predict device performance.