When a transition-metal compound is subject to high pressure, its electronic spin state can change, which in turn can change its material properties. That spin-state crossover is of geophysical relevance because of the iron-bearing minerals in Earth’s mantle and because material properties affect the speed of seismic waves. But the most abundant mantle mineral—Fe-bearing magnesium silicate perovskite (Pv)—is a challenge to study, because it contains three nonequivalent types of Fe atom.
Experiments on spin states under pressure probe the electron configuration only indirectly, so computational studies are necessary to resolve experimental ambiguities and to connect measurements with the correct interpretations and implications. Researchers led by Renata Wentzcovitch (University of Minnesota) have now done a computational study of Fe atoms in Pv.1 They found that one of the three types of Fe undergoes a spin-state crossover, which has a significant effect on seismic waves and on mantle convection.
Spin-state crossover...
