A superconductor is a material that conducts electricity without loss, but only at very low temperatures. On such a material, researchers placed a film of magnetic material one atom thick. Magnetism and superconductivity usually don't get along, and physicists hoped to see something unusual at the interface between the two materials.

It turned out that the film behaves as an insulator and barely affects the layer beneath. The superconducting properties remained the same as those of the pure material: the same electron binding energy, the same response to temperature and magnetic field. Even the vortices, tiny magnetic tornadoes that form in a superconductor, looked identical.

The only difference was found at the dirty edges of the film, but clean edges showed no such effect. This means the effect is random, not an intrinsic property of the material. The magnetic layer turned out to be too weakly coupled to the superconductor to create new quantum states.