Mechanisms for Pressure-Induced Isostructural Phase Transitions in EuO
| Autor: | Jacques K. Desmarais, Alessandro Erba, John S. Tse, Yuanming Pan, Bartolomeo Civalleri |
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| Rok vydání: | 2021 |
| Předmět: |
Physics
Phase transition Valence (chemistry) Condensed matter physics General Physics and Astronomy 01 natural sciences Atomic orbital 0103 physical sciences Density of states Condensed Matter::Strongly Correlated Electrons Density functional theory Strongly correlated material Isostructural 010306 general physics Electronic band structure |
| Zdroj: | Physical review letters. 126(19) |
| ISSN: | 1079-7114 |
| Popis: | We study pressure-induced isostructural electronic phase transitions in the prototypical mixed valence and strongly correlated material EuO using the global-hybrid density functional theory. The simultaneous presence in the valence of highly localized $d$- and $f$-type bands and itinerant $s$- and $p$-type states, as well as the half-filled $f$-type orbital shell with seven unpaired electrons on each Eu atom, have made the description of the electronic features of this system a challenge. The electronic band structure, density of states, and atomic oxidation states of EuO are analyzed in the 0--50 GPa pressure range. An insulator-to-metal transition at about 12 GPa of pressure was identified. The second isostructural transition at approximately 30--35 GPa, previously believed to be driven by an oxidation from Eu(II) to Eu(III), is shown instead to be associated with a change in the occupation of the Eu $d$ orbitals, as can be determined from the analysis of the corresponding atomic orbital populations. The Eu $d$ band is confined by the surrounding oxygens and split by the crystal field, which results in orbitals of ${e}_{g}$ symmetry (i.e., ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ and ${d}_{2{z}^{2}\ensuremath{-}{x}^{2}\ensuremath{-}{y}^{2}}$, pointing along the Eu-O direction) being abruptly depopulated at the transition as a means to alleviate electron-electron repulsion in the highly compressed structures. |
| Databáze: | OpenAIRE |
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