Supercurrent diode effect in thin film Nb tracks

We demonstrate nonreciprocal critical current in 65 nm thick polycrystalline and epitaxial Nb thin films patterned into tracks. The nonreciprocal behavior gives a supercurrent diode effect, where the current passed in one direction is a supercurrent and the other direction is a normal state (resistive) current. We attribute fabrication artifacts to creating the supercurrent diode effect in our tracks. We study the variation of the diode effect with temperature and the magnetic field and find a dependence with the width of the Nb tracks from 2 to 10 mu m. For both polycrystalline and epitaxial samples, we find that tracks of width 4 mu m provide the largest supercurrent diode efficiency of up to approximate to 30%, with the effect reducing or disappearing in the widest tracks of 10 mu m. We propose a model based on the limiting contributions to the critical current density to explain the track width dependence of the induced supercurrent diode effect. It is anticipated that the supercurrent diode will become a ubiquitous component of the superconducting computer. (c) 2023 Author(s).

Automated summary

We demonstrate the nonreciprocal critical current in Nb thin films and explain the supercurrent diode effect in the tracks. The diode effect varies with temperature and magnetic field, and depends on the width of the Nb tracks. The supercurrent diode is proposed to become a ubiquitous component of the superconducting computer.