title: Reentrant valence transition in EuO at high pressures: beyond the bond-valence model.
abstract: The pressure-dependent relation between Eu valence and lattice structure in model compound EuO is studied with synchrotron-based x-ray spectroscopic and diffraction techniques. Contrary to expectation, a 7% volume collapse at ≈45  GPa is accompanied by a reentrant Eu valence transition into a lower valence state. In addition to highlighting the need for probing both structure and electronic states directly when valence information is sought in mixed-valent systems, the results also show that widely used bond-valence methods fail to quantitatively describe the complex electronic valence behavior of EuO under pressure.
authors.affiliation: Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA. narcizo.souza@lnls.br
authors.forename: N M
authors.initials: NM
authors.lastname: Souza-Neto
authors.forename: J
authors.initials: J
authors.lastname: Zhao
authors.forename: E E
authors.initials: EE
authors.lastname: Alp
authors.forename: G
authors.initials: G
authors.lastname: Shen
authors.forename: S V
authors.initials: SV
authors.lastname: Sinogeikin
authors.forename: G
authors.initials: G
authors.lastname: Lapertot
authors.forename: D
authors.initials: D
authors.lastname: Haskel