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arXiv · 2308.02855

Emergent electronic landscapes in a novel valence-ordered nickelate with tri-component nickel coordination

Aravind Raji·Zhengang Dong·Victor Porée·Alaska Subedi·Xiaoyan Li·Bernat Mundet·Lucia Varbaro·Claribel Domínguez·Marios Hadjimichael·Bohan Feng·Alessandro Nicolaou·Jean-Pascal Rueff·Danfeng Li·Alexandre Gloter
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Abstract

The metal-hydride-based topochemical reduction process has produced novel thermodynamically unstable phases across various transition metal oxide series with unusual crystal structures and non-trivial ground states. Here, by such an oxygen (de-) intercalation method we synthesis a novel samarium nickelate with ordered nickel valences associated with tri-component coordination configurations. This structure, with a formula of Sm$_{9}$Ni$_{9}$O$_{22}$ as revealed by four-dimensional scanning transmission electron microscopy, emerges from the intricate planes of {303}$_{\text{pc}}$ ordered apical oxygen vacancies. X-ray spectroscopy measurements and ab-initio calculations show the coexistence of square-planar, pyramidal and octahedral Ni sites with mono-, bi- and tri-valences. It leads to an intense orbital polarization, charge-ordering, and a ground state with a strong electron localization marked by the disappearance of ligand-hole configuration at low-temperature. This new nickelate compound provides another example of previously inaccessible materials enabled by topotactic transformations and presents a unique platform where mixed Ni valence can give rise to exotic phenomena.

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Aravind Raji, Zhengang Dong, Victor Porée, Alaska Subedi, Xiaoyan Li, Bernat Mundet, Lucia Varbaro, Claribel Domínguez, Marios Hadjimichael, Bohan Feng, Alessandro Nicolaou, Jean-Pascal Rueff, Danfeng Li, Alexandre Gloter. 2023-08-05. Emergent electronic landscapes in a novel valence-ordered nickelate with tri-component nickel coordination. https://doi.org/10.1021/acsnano.3c07614

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