Superconductors are materials that conduct electricity without loss, but their properties are usually fixed. In the new work, scientists made a device resembling a crossroads of two superconducting tracks. By applying a weak magnetic field perpendicular to this crossroads, they were able to change the current the device can carry by a factor of four. It's like regulating the flow of water in a pipe by slightly tilting it.
The scientists also found that the temperature at which the transition to the superconducting state occurs changes upon switching, and the dependence of the current on the magnetic field is non-monotonic. This is explained by the emergence of special magnetic vortices at the crossroads, which enter and repel each other in different ways.
Such a device could become the basis for compact superconducting microchips where current needs to be controlled with minimal energy expenditure.
Superconductors are already used in MRI scanners and particle accelerators, but for logic circuits they lacked controllable switches — now that's possible.