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Magnetic Collapse in Transition Metal Oxides at High Pressure: Implications for the Earth
1R. E. Cohen and I. I. Mazin, Geophysical Laboratory and Center for High-Pressure Research, Carnegie Institution of Washington, 5251 Broad Branch Road, NW, Washington, DC 20015, USA. D. G. Isaak, Institute of Geophysics and Planetary Physics, University of California at Los Angeles, Los Angeles, CA 90095-1567, and Department of Mathematics and Physics, Azusa Pacific University, Azusa, CA 91702, USA.
Abstract:
Magnetic collapse in transition metal ions is predicted from first-principles computations at pressures reached in the Earth's lower mantle and core. Magnetic collapse would lead to marked changes in geophysically important properties, such as elasticity and conductivity, and also to different geochemical behavior, such as element partitioning, than estimated by extrapolating low-pressure data, and thus change the understanding of Earth's structure and evolution. Magnetic collapse results from band widening rather than from changes in crystal field splitting under pressure. Seismic anomalies in the outer core and the lowermost mantle may be due to magnetic collapse of ferrous iron, dissolved in iron liquid in the outer core, and in solution in magnesiowustite in the lowermost mantle.