ABSTRACT Superconducting diodes enable nonreciprocal transport in cryogenic circuits. Most existing devices rely on engineered Josephson junctions, strong spin–orbit coupling, or complex multilayer stacks and typically require an applied magnetic field, which limits straightforward thin‐film integration. Here we demonstrate a field‐free, memory‐programmable superconducting diode in a simple planar NbN/AlN/permalloy microbridge. The remanent in‐plane magnetization of the ferromagnetic overlayer programs the diode polarity and preserves it without any external field. Edge‐localized stray fields generate opposite‐sign out‐of‐plane induction at the two edges and set an asymmetric flux landscape. The transport‐current Lorentz force then biases vortex dynamics, yielding direction‐dependent critical currents and rectification efficiencies up to ∼40%. The device is planar, chemically robust, and compatible with standard NbN thin‐film processing, enabling practical integration of programmable nonreciprocal elements into superconducting circuits.
Zapata et al. (Thu,) studied this question.