An ordinary superconductor is like a squad of soldiers marching in pairs: electrons pair up, and their spins (internal 'tops') point in opposite directions. A magnetic field easily flips such pairs, destroying superconductivity.
In UTe₂, things are different. There, electron pairs have spins pointing in the same direction, like dance partners holding hands and spinning in the same rhythm. When physicists applied a magnetic field along the c-axis, the spins barely changed up to 5 tesla (about 100,000 times stronger than Earth's magnetic field), and then quickly returned to their normal state. Superconductivity persisted even at fields above this threshold. The researchers noticed that when the field is oriented so that the pair spins align with it, superconductivity becomes more robust.
This behavior is reminiscent of superfluid helium-3—a liquid that flows without friction at ultra-low temperatures. Perhaps UTe₂ is a solid-state cousin of this exotic liquid. Understanding its properties could help create devices where spins can be manipulated without destroying the quantum state.
The stubborn tops in UTe₂ resist the magnetic field until the very end, then give in all at once, but superconductivity remains. This is a window into materials that could become the foundation of future quantum computers.
A magnetic field of 5 tesla, at which the spins in UTe₂ abruptly change behavior, is roughly a million times stronger than the field of a refrigerator magnet.
In the series 'The Expanse,' superconductors are used to create efficient engines and shields — exotic superconductors like UTe₂ could make such technology more real.