Switching Lanes: A Zero-Field Leap for Superconducting Logic

Superconducting electronics promise a future where processors sip energy rather than guzzling it, yet a significant hurdle has remained: the practical diode. Essential for directing current, these nonreciprocal elements typically demand bulky external magnetic fields to function, rendering them cumbersome for scalable circuits. Now, a research team has circumvented this limitation, demonstrating a polarity-reversible Josephson diode that operates robustly at zero field.

The innovation lies in a nanoscale sandwich—a vertically stacked van der Waals junction. The device pairs an Ising superconductor (NbSe₂) with an itinerant ferromagnetic layer (Fe₃GeTe₂, or FGT). By carefully optimising the thickness and magnetic state of the FGT layer, the researchers achieved a ‘tunable’ asymmetry. This allows the diode not only to rectify current with an impressive efficiency of 34.1% but also to reverse its polarity on demand, all without the aid of an external magnet.

Crucially, this is not merely a theoretical exercise in materials science. The team successfully utilised this reconfigurable behaviour to construct an XOR logic gate, a fundamental building block of modern computation. This development establishes a viable route toward non-dissipative electronics, offering a tantalising glimpse of the architecture required for next-generation quantum processors and beyond-Moore’s-law systems.