Probing Nickelate Superconductors at the Atomic Scale: A STEM Review

Abstract The discovery of nickelate superconductors, including doped infinite-layer (IL) nickelates R NiO 2 ( R = La, Pr, Nd), layered square-planar nickelate Nd 6 Ni 5 O 12 , and the Ruddlesden–Popper (RP) phase La 3 Ni 2 O 7 , has spurred immense interest in fundamental research and potential applications. Scanning transmission electron microscopy (STEM) has proven crucial for understanding structure–property correlations in these diverse nickelate superconducting systems. In this review, we summarize the key findings from various modes of STEM, elucidating the mechanism of different nickelate superconductors. We also discuss future perspectives on emerging STEM techniques for unraveling the pairing mechanism in the “nickel age” of superconductivity.