Magnetic fields are generally known to destroy superconductivity in a material. However, in exceptional cases, they can lead to what is known as “re-entrant superconductivity”—where superconductivity disappears as expected, but then unexpectedly returns when the magnetic field is increased further.

This behavior is sometimes seen in bulk, three-dimensional materials, but now, in a study published in Science Advances, a team led by the RIKEN Center for Emergent Matter Science (CEMS) in Japan has seen the phenomenon in a very thin conducting layer at the boundary between two insulating oxide materials. Because oxide interfaces can be precisely engineered and controlled, the discovery provides a new platform for investigating unconventional forms of superconductivity and the quantum mechanisms that allow it to survive under unusual conditions.