Usually, superconductivity is a story about cold. The lower the temperature, the easier it is for electrons to pair up and flow without resistance. But in a new study, physicists grew thin films of nickelates doped with europium and saw the opposite picture. At temperatures below 2.6 K, the sample behaved like an ordinary metal with resistance. But as soon as it was warmed a bit, the resistance dropped to zero. Superconductivity switched on from heat.
This inverse transition worked in a narrow corridor: from 2.6 to 5.4 K. Above that, the material became normal again. It was like an 'island' of superconductivity surrounded by a non-superconducting sea. Moreover, the island's boundaries could be shifted not only by temperature but also by a magnetic field or simply by increasing the current through the sample.
The authors suggest that heating changes the balance between two competing magnetic influences. One is related to europium's own magnetism and can break Cooper pairs (the bound electron states that carry the superconducting current). The other, an effective field arising from the compensation of these moments, under certain conditions stabilizes the superconducting state instead. As temperature rises, the second influence temporarily wins, and superconductivity appears. With even more heating, the first wins again, and everything returns to normal.
This discovery turns the conventional view of heat as an enemy of quantum coherence (the consistency of quantum states) on its head. Instead of destroying an ordered state, thermal fluctuations can create it. This is not just a curiosity: it's a new tool for engineering quantum phases. Devices based on such materials could switch between states not by cooling to ultra-low temperatures but by heating — which is technically simpler and opens up unexpected scenarios for superconducting electronics.
The temperature of 2.6 K at which superconductivity switched on is only a couple of degrees warmer than the cosmic microwave background, which has cooled for 13.8 billion years since the Big Bang.
In Peter Watts's novel 'Blindsight', alien life forms use magnetic fields for coherent quantum processes — much like europium controls superconductivity in these nickelates.