Oxygen sublattice disorder and valence state modulation in infinite-layer nickelate superlattices

Fuente: arXiv
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Hauptverfasser: Ortiz, R. A., Enderlein, N., Fürsich, K., Pons, R., Radhakrishnan, P., Schierle, E., Wochner, P., Logvenov, G., Cristiani, G., Hansmann, P., Keimer, B., Benckiser, E.
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Veröffentlicht: 2025
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author Ortiz, R. A.
Enderlein, N.
Fürsich, K.
Pons, R.
Radhakrishnan, P.
Schierle, E.
Wochner, P.
Logvenov, G.
Cristiani, G.
Hansmann, P.
Keimer, B.
Benckiser, E.
author_facet Ortiz, R. A.
Enderlein, N.
Fürsich, K.
Pons, R.
Radhakrishnan, P.
Schierle, E.
Wochner, P.
Logvenov, G.
Cristiani, G.
Hansmann, P.
Keimer, B.
Benckiser, E.
contents The family of infinite-layer nickelates promises important insights into the mechanism of unconventional superconductivity. Since superconductivity has so far only been observed in epitaxial thin films, heteroepitaxy with the substrate or a capping layer possibly plays an important role. Here, we use soft x-ray spectroscopy to investigate superlattices as a potential approach for a targeted material design of high-temperature superconductors. We observe modulations in valence state and oxygen coordination in topotactically reduced artificial superlattices with repeating interfaces between nickelate layers and layers of materials commonly used as substrates and capping layers. Our results show that depending on the interlayer material metallic conductivity akin to the parent infinite-layer compounds is achieved. Depth-resolved electronic structure measured by resonant x-ray reflectivity reveals a reconstructed ligand field and valence state at the interface, which is confined to one or two unit cells. The central layers show characteristics of monovalent nickel, but linear dichroism analysis reveals considerable disorder in the oxygen removal sites. We observe a quantitative correlation of this disorder with the interlayer material that is important for future modeling and design strategies.
format Preprint
id arxiv_https___arxiv_org_abs_2502_03873
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Oxygen sublattice disorder and valence state modulation in infinite-layer nickelate superlattices
Ortiz, R. A.
Enderlein, N.
Fürsich, K.
Pons, R.
Radhakrishnan, P.
Schierle, E.
Wochner, P.
Logvenov, G.
Cristiani, G.
Hansmann, P.
Keimer, B.
Benckiser, E.
Superconductivity
Materials Science
Strongly Correlated Electrons
The family of infinite-layer nickelates promises important insights into the mechanism of unconventional superconductivity. Since superconductivity has so far only been observed in epitaxial thin films, heteroepitaxy with the substrate or a capping layer possibly plays an important role. Here, we use soft x-ray spectroscopy to investigate superlattices as a potential approach for a targeted material design of high-temperature superconductors. We observe modulations in valence state and oxygen coordination in topotactically reduced artificial superlattices with repeating interfaces between nickelate layers and layers of materials commonly used as substrates and capping layers. Our results show that depending on the interlayer material metallic conductivity akin to the parent infinite-layer compounds is achieved. Depth-resolved electronic structure measured by resonant x-ray reflectivity reveals a reconstructed ligand field and valence state at the interface, which is confined to one or two unit cells. The central layers show characteristics of monovalent nickel, but linear dichroism analysis reveals considerable disorder in the oxygen removal sites. We observe a quantitative correlation of this disorder with the interlayer material that is important for future modeling and design strategies.
title Oxygen sublattice disorder and valence state modulation in infinite-layer nickelate superlattices
topic Superconductivity
Materials Science
Strongly Correlated Electrons
url https://arxiv.org/abs/2502.03873