Intrinsic magnetism in superconducting infinite-layer nickelates

Abstract

The discovery of superconductivity in Nd0.8Sr0.2NiO2 (ref. 1) introduced a new family of layered nickelate superconductors that has now been extended to include a range of strontium doping2,3, praseodymium or lanthanum in place of neodymium4–7, and the five-layer compound Nd6Ni5O12 (ref. 8). A number of studies have indicated that electron correlations are strong in these materials9–15, a feature that often leads to the emergence of magnetism. Here we report muon spin rotation/relaxation studies of a series of superconducting infinite-layer nickelates. Regardless of the rare earth ion or doping, we observe an intrinsic magnetic ground state arising from local moments on the nickel sublattice. The coexistence of magnetism—which is likely to be antiferromagnetic and short-range ordered—with superconductivity is reminiscent of some iron pnictides16 and heavy fermion compounds17, and qualitatively distinct from the doped cuprates18. Measurements of four different infinite-layer nickelates show that magnetic behaviour coexists with superconductivity. This is different from what is seen in cuprates, giving a strong distinction between the two classes of oxide superconductors.