Structural and Electronic Transitions in Liquid FeO Under High Pressure

International audienceInvestigation of the structural and electronic properties of solid and liquid FeO at high pressures and temperatures is of great interest in geophysics and planetary sciences, as well as in condensed-matter physics. FeO is a typical Mott insulator under ambient conditions and a prototypical highly correlated transition metal oxide. Different electronic and structural transitions occur in FeO under compression at ambient temperature. Along with other transition metal oxides, it undergoes a spin crossover and it metalizes under pressure (Ohta et al., 2012). One of the open questions is to understand if the metalization and the transition from high spin to low spin state in the solid state are simply concomitant or more intricately related (Greenberg et al., 2020; Leonov, 2015; Ozawa, Hirose, et al., 2011). Similar to the case of other crystalline planetary materials, the spin crossover has received much attention in the solid state (see reviews by Badro [2014] and Lin et al. [2013]) but its effects in the liquid phase are still relatively poorly known (Holmstrom & Stixrude, 2016). An improved knowledge of physical properties of iron alloys in their liquid state under extreme conditions is required to understand the composition and properties of planetary cores, as well as to constrain scenarios of planetary differentiation. FeO represents an important end-member, as O is expected to be a major light element in Earth's core (Badr