Following the discovery of superconductivity in hole-doped NdNiO2 infinite-layer thin films, extensive research has been conducted particularly to compare these materials with cuprates. Superconductivity has also been observed in nickelate thin films with other rare-earth elements like Pr and La, but not in their bulk forms, suggesting a critical role for substrate-induced strain/interface or dimensionality effects. In this study, we use water-soluble (Ca,Sr)3Al2O6 sacrificial layers to fabricate freestanding perovskite nickelate membranes and explore topotactic reduction without the SrTiO3 substrate as a template. NdNiO3-based heterostructure membranes transferred from a LaAlO3 substrate exhibit better metallic behavior and higher hysteresis than those transferred from SrTiO3, owing to the different strain states that the NdNiO3 layer experience when grown on these two substrates. Despite the expected X-ray diffraction shifts, membranes reduced with CaH2 display insulating characteristics, similar to bulk infinite-layer nickelates. Our findings strongly indicate that a template is necessary to stabilize a coherent and robust infinite-layer phase with optimal transport properties.
@article{arxiv.2405.10644,
title = {Freestanding perovskite and infinite-layer nickelate membranes},
author = {Hoshang Sahib and Laurent Schlur and Kumara Cordero and Nathalie Viart and David Pesquera and Daniele Preziosi},
journal= {arXiv preprint arXiv:2405.10644},
year = {2025}
}