Decoding Superconductivity in La3Ni2O7−δ Thin Films via Ozone-Driven Structure and Oxidation Tuning
Abstract
The discovery of superconductivity in bulk Ruddlesden-Popper La 3 Ni 2 O 7 (LNO327) under high hydrostatic pressure has redefined the recent experimental consensus that nickelate superconductivity is restricted to systems with a 3d 9 electronic configuration and square-planar coordination. However, the structural and electronic prerequisites for stabilizing superconductivity, whether under pressure or at ambient conditions in the case of thin films, remain poorly understood, largely due to the metastable nature of the LNO327 phase. Here, we present a detailed structural study of epitaxial La 3 Ni 2 O 7-δ thin films by using scanning transmission electron microscopy (STEM) combined with electron energy loss spectroscopy (EELS). Grown via pulsed laser deposition onto SrLaAlO 4 substrates, those films exhibit distinct superconducting properties as a function of the different post-annealing conditions used. By correlating the rich landscape of stacking polymorphs with transport behavior, this work establishes a framework for understanding the metastable superconducting phase in bilayer nickelate thin films. In particular, we found that the LNO-1313 stacking polymorph does not support superconductivity, suggesting it is not a superconducting phase. Our findings underscore the critical role of homogeneity in oxygen stoichiometry, epitaxial strain and structural motif in stabilizing superconductivity, offering a clear pathway for designing ambient-pressure superconducting nickelates.
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BibTeX
@article{flavenot2026decoding,
title = {{Decoding Superconductivity in La3Ni2O7−δ Thin Films via Ozone-Driven Structure and Oxidation Tuning}},
author = {Mathieu Flavenot and Hoshang Sahib and Jérôme Robert and Marc Lenertz and Gilles Versini and Laurent Schlur and Alexandre Gloter and Nathalie Viart and Daniele Preziosi},
journal = {Small Structures},
year = {2026},
month = aug,
doi = {10.1002/sstr.70542},
url = {https://univoak.hal.science/hal-05758256v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Decoding Superconductivity in La3Ni2O7−δ Thin Films via Ozone-Driven Structure and Oxidation Tuning
AU - Mathieu Flavenot
AU - Hoshang Sahib
AU - Jérôme Robert
AU - Marc Lenertz
AU - Gilles Versini
AU - Laurent Schlur
AU - Alexandre Gloter
AU - Nathalie Viart
AU - Daniele Preziosi
PY - 2026
DA - 2026/08/05
JO - Small Structures
DO - 10.1002/sstr.70542
UR - https://univoak.hal.science/hal-05758256v1
AB - The discovery of superconductivity in bulk Ruddlesden-Popper La 3 Ni 2 O 7 (LNO327) under high hydrostatic pressure has redefined the recent experimental consensus that nickelate superconductivity is restricted to systems with a 3d 9 electronic configuration and square-planar coordination. However, the structural and electronic prerequisites for stabilizing superconductivity, whether under pressure or at ambient conditions in the case of thin films, remain poorly understood, largely due to the metastable nature of the LNO327 phase. Here, we present a detailed structural study of epitaxial La 3 Ni 2 O 7-δ thin films by using scanning transmission electron microscopy (STEM) combined with electron energy loss spectroscopy (EELS). Grown via pulsed laser deposition onto SrLaAlO 4 substrates, those films exhibit distinct superconducting properties as a function of the different post-annealing conditions used. By correlating the rich landscape of stacking polymorphs with transport behavior, this work establishes a framework for understanding the metastable superconducting phase in bilayer nickelate thin films. In particular, we found that the LNO-1313 stacking polymorph does not support superconductivity, suggesting it is not a superconducting phase. Our findings underscore the critical role of homogeneity in oxygen stoichiometry, epitaxial strain and structural motif in stabilizing superconductivity, offering a clear pathway for designing ambient-pressure superconducting nickelates.
SN - 2688-4062
ER -