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

TL;DR

This paper demonstrates a highly efficient, field-free superconducting diode effect in heterostructures by engineering geometric asymmetry and utilizing perpendicular magnetization, advancing superconducting electronics.

Contribution

It introduces a novel, scalable platform for high-performance, field-free superconducting diodes using geometric asymmetry and magnetic pinning in heterostructures.

Findings

Diode efficiencies surpass previous field-free values

Enhanced nonreciprocity from vortex entry and pinning mechanisms

Supports applications in cryogenic spintronics and quantum electronics

Abstract

The superconducting diode effect (SDE)- manifested as directional, dissipationless supercurrents - is pivotal for realizing energy-efficient superconducting logic and memory technologies. Achieving high-efficiency SDE without external magnetic fields, however, remains a fundamental challenge. Here, we report a strongly enhanced, field-free SDE in Pt/Co/Nb heterostructures, 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. Temperature- and field-dependent transport measurements, supported by micromagnetic simulations, reveal that the enhanced nonreciprocity stems from three cooperative mechanisms: asymmetric vortex entry, localized magnetic pinning, and Lorentz-force imbalance. These findings establish a scalable, CMOS-compatible platform for high-performance superconducting rectifiers, offering new opportunities for cryogenic spintronics and quantum electronics.