Spin crossover in solid and liquid (Mg,Fe)O from first-principles molecular dynamics

Abstract:

Ferropericlase, (Mg,Fe)O, is a major constituent of the Earth's lower
mantle. Understanding the properties of this component is important
not only in the solid state, but also in the molten state, as the
planet almost certainly hosted an extensive magma ocean in Hadean
times. Using first-principles molecular dynamics simulations,
thermodynamic integration, and adiabatic switching, we present a phase
diagram of the spin crossover, i.e., the pressure-induced collapse of
magnetic moments, in both solid and liquid (Mg,Fe)O. Furthermore, we
compute the thermodynamic properties and the electrical conductivity
of the crystal and melt over a wide range of conditions. We then
present the geophysical implications of our findings.