Towards Higher-Crystallinity Superconducting Infinite-Layer Nickelates*

The recent discovery of superconductivity in the infinite-layer nickelates Re_1–xSr_xNiO₂ (Re = Nd, Pr)^1,2 presents an important materials challenge to further improve the crystallinity and synthetic reproducibility of this difficult material,^3,4 so that intrinsic investigations of the superconducting and normal-state properties of this system can be initiated. After careful optimization of the growth and reduction conditions, we have identified key parameters for further improving crystallinity and established a reproducible method to stabilize Nd_1–xSr_xNiO₂ (001) epitaxial thin films on SrTiO₃ (001) substrate by pulsed-laser deposition and CaH₂-assisted topochemical reduction. The details of the optimization process and the dependence of the structural and superconducting properties on the growth conditions will be discussed.

1 Li, D. et al., Nature 572, 624 (2019).
2 Osada, M. et al., Nano Lett. 20, 5735 (2020).
3 Wang, B.-X. et al., Phys. Rev. Mater. 4, 084409 (2020).
4 Lee, K. et al., APL Mater. 8, 041107 (2020).