Uncovering the Nature of Superconductivity in Undoped Infinite Layer Nickelates

The collection of nickel-based superconductors has greatly expanded in recent years, particularly in the hole-doped infinite layer nickelates (R_1-xA_xNiO₂; R = lanthanide, A = Sr, Ca, Eu) [1–4]. The diversity of hole-doped nickelates stem from the various combinations of lanthanide cations and divalent dopants that can be incorporated into the infinite layer structure. Nevertheless, they all possess a phase diagram reminiscent to the cuprates, notably a superconducting dome with hole doping between 0.12 < x < 0.27 [5]. However, unlike the cuprates, there is evidence of superconductivity in the undoped infinite layer nickelates [2,6]. Superconductivity in undoped infinite layer nickelates has remained elusive given the challenges associated with nickelate synthesis. Here we report on improvements to the reproducibility of superconductivity in undoped LaNiO₂ and NdNiO₂ and demonstrate the highly two-dimensional nature of undoped superconductivity.



References

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[6] C. T. Parzyck et al., (2024).