A new kind of metal in the deep Earth

ferropericlase

The crushing pressures and intense temperatures in Earth’s deep interior squeeze atoms and electrons so closely together that they interact very differently. With depth materials change. New experiments and supercomputer computations discovered that iron oxide undergoes a new kind of transition under deep Earth conditions. Iron oxide, FeO, is a component of the second most abundant mineral at Earth’s lower mantle, ferropericlase.

The finding, published in an upcoming issue of Physical Review Letters, could alter our understanding of deep Earth dynamics and the behavior of the protective magnetic field, which shields our planet from harmful cosmic rays.

Ferropericlase contains both magnesium and iron oxide. To imitate the extreme conditions in the lab, the team including coauthor Ronald Cohen of Carnegie’s Geophysical Laboratory, studied the electrical conductivity of iron oxide to pressures and temperatures up to 1.4 million times atmospheric pressure and 4000°F—on par with conditions at the core-mantle boundary. They also used a new computational method that uses only fundamental physics to model the complex many-body interactions among electrons. The theory and experiments both predict a new kind of metallization in FeO.

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