Superconductivity with a Twist

Superconductivity and magnetism are typically antithetical forms of order. After all, in conventional superconductors, magnetic impurities are destructive to superconductivity as they break Cooper pairs [1]. But the discovery in 1979 of so-called heavy fermion superconductivity, found near an antiferromagnetic phase, led to a shift in thinking on this subject [2]. Since then, some of the most important classes of superconductors have been found in proximity to magnetism, including not only heavy-fermion superconductors, but also organic superconductors, cuprates, and iron-based superconductors [3]. All of them have similar phase diagrams, in which, either by pressure or chemical substitution, a magnetic phase is suppressed, giving rise to a superconducting phase. This has led to the suggestion that an effective search strategy for discovering new superconductors is to identify a stoichiometric phase that is magnetic, and then find a way to hinder magnetism [4]. Following such an approach, a team led by Jin-Guang Cheng at the Beijing National Laboratory, China, now reports the discovery of the first superconductor based on manganese, an element whose magnetism was thought to be too strong to allow superconductivity. By suppressing magnetism with a large applied pressure, the authors found that manganese phosphide (MnP) can become superconducting at a critical temperature of 1 K.