Magnetic and spin transitions in wüstite: A synchrotron Mössbauer spectroscopic study

Maki Hamada, Seiji Kamada, Eiji Ohtani, Takaya Mitsui, Ryo Masuda, Tatsuya Sakamaki, Nanami Suzuki, Fumiya Maeda, Masahide Akasaka

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

This is a Mössbauer study of wüstite at pressures above 200 GPa using synchrotron Mössbauer spectroscopy. Synthetic Fe0.96O-wüstite was investigated at 91(2), 95(4), 109(2), 114.5(3), 131.1(7), 133.2(2), 155(2), 167(2), 193(2) and 203(1) GPa at 300 K at the SPring-8 BL11XU beamline. The Mössbauer spectrum at 91 GPa consists of both magnetic and nonmagnetic components. The magnetic high-spin component decreases gradually with increasing pressure from 91 to 203 GPa, while the nonmagnetic low-spin component increases with pressure in the same pressure range. The result suggests that the spin state of Fe in the outer core at pressures above 203 GPa is the low-spin state. If oxygen exists in the core, the low-spin Fe-O bonding is shorter than high-spin Fe-O bonding, suggesting dense Fe-O liquid in the Earth's outer core. The gradual increase of the density of the metallic liquid with depth by the spin transition of Fe-O bonding in the shallow outer core region will stabilize the outer core against thermal convection.

Original languageEnglish
Article number155165
JournalPhysical Review B
Volume93
Issue number15
DOIs
Publication statusPublished - 2016 Apr 28

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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