Electronic Spin transition in FeO${}_2$: evidence for Fe(II) with peroxide O${}_2^{2-}$

Abstract

The discovery of FeO${}_2$ containing more oxygen than hematite (Fe${}_2$O${}_3$) that was previously believed to be the most oxygen rich iron compounds, has important implications on the study of the deep lower mantle compositions. Compared to other iron compounds, there are limited reports on FeO${}_2$ making studies of its physical properties of great interest in fundamental condensed matter physics and geoscience. Even the oxidation state of Fe in FeO${}_2$ is the subject of debate in theoretical works and there have not been reports from experimental electronic and magnetic properties measurements. Here, we report the pressure-induced spin state transition from synchrotron experiments and our computational results explain the underlying mechanism. Using density functional theory and dynamical mean field theory, we calculated spin states of Fe with volume and Hubbard interaction $U$ change, which clearly demonstrate that Fe in FeO${}_2$ consists of Fe(II) and peroxide O${}_2^{2-}$. Our study suggests that localized nature of both Fe 3$d$ orbitals and O${}_2$ molecular orbitals should be correctly treated for unveiling the structural and electronic properties of FeO${}_2$.

arXiv comment7 pages, 4 figures

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Cited by in corpus (6)

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• Revealing the complex nature of bonding in binary high-pressure compound FeO${}_2$
• Metal-insulator transition and local-moment collapse in negative charge-transfer CaFeO${}_3$ under pressure
• Anomalous thermal properties and spin crossover of ferromagnesite (Mg,Fe)CO3
• Metallic nature and site-selective magnetic collapse in iron oxide Fe4O5 at the extreme conditions of Earth's deep interior
• Interplay of electronic correlations and chemical bonding in FeN${}_2$ under pressure