Physicists in the UK have shown that a superconductor can transfer a magnetic field from a magnet to a non-magnetic metal without becoming magnetized itself. The surprising effect is not predicted by any prevailing theory of superconductivity and could have important applications in the emerging field of superconducting spintronics.

In a conventional superconductor, electrical current is carried by Cooper pairs of electrons. The electron spins in a pair point in opposite directions and therefore the pair has zero net spin. The application of a strong magnetic field destroys superconductivity by encouraging both spins to point in the same direction, which tears the Cooper pairs apart. Weak magnetic fields cannot exist within a conventional superconductor, which acts to expel magnetic-field lines. As a result, superconductivity and magnetism are usually seen as mutually exclusive phenomena.

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