Field‐Free Superconducting Diode Enabled by Geometric Asymmetry and Perpendicular Magnetization

Abstract The superconducting diode effect (SDE), which manifests as directional, dissipationless supercurrents, is pivotal for realizing energy‐efficient superconducting logic and memory technologies. However, achieving high‐efficiency SDE without external magnetic fields remains a fundamental challenge. In this study, a strongly enhanced, field‐free SDE in Pt/Co/Nb heterostructures are proposed, enabled by the interplay of engineered geometric asymmetry and stray fields from a perpendicularly magnetized Co layer. This configuration promotes directional vortex entry and spatially selective pinning, yielding diode efficiencies that exceed all previously reported field‐free values in ferromagnet/superconductor multilayers. Temperature‐ and field‐dependent transport measurements, supported by micromagnetic simulations, reveal that the enhanced nonreciprocity results from three cooperative mechanisms: asymmetric vortex entry, localized magnetic pinning, and Lorentz‐force imbalance. These findings establish a CMOS‐compatible platform for high‐performance superconducting rectifiers, offering new opportunities for cryogenic spintronics and quantum electronics.