) nickelates*

The recent discovery of superconductivity in a hole-doped infinite layer nickelate has spurred the reexamination of how nickelate physics may be amenable to stabilizing new superconducting phases [1]. The nickelate identified is isostructural to the superconducting cuprates and lies squarely in the superconducting regime of the simple phase diagram by Zhang [2] but disentangling the electronic from the structural contributions presents a key challenge. We have stabilized, for the first time, the Ruddlesden-Popper nickelates (Nd_n+1Ni_nO_3n+1) in thin film form up to n = 6. We will discuss how tuning of the Ruddlesden-Popper order alters the electronic ground states of the system including the nickel 3d occupancy and effects on the canonical metal-to-insulator transition.

[1] D. Li et al., Nature 572, 624-627 (2019).
[2] J. Zhang et al., Nature Physics 13, 964-869 (2017).