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Pressure-induced sp...
Pressure-induced spin-state transition of iron in magnesiowustite (Fe,Mg)O
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- Leonov, I. (författare)
- University of Augsburg, Germany; National University of Science and Technology MISIS, Russia
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- Ponomareva, A. V. (författare)
- National University of Science and Technology MISIS, Russia
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- Nazarov, R. (författare)
- Lawrence Livermore National Lab, CA 94551 USA
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- Abrikosov, Igor (författare)
- Linköpings universitet,Teoretisk Fysik,Tekniska fakulteten
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(creator_code:org_t)
- AMER PHYSICAL SOC, 2017
- 2017
- Engelska.
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Ingår i: Physical Review B. - : AMER PHYSICAL SOC. - 2469-9950 .- 2469-9969. ; 96:7
- Relaterad länk:
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https://liu.diva-por... (primary) (Raw object)
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- We present a detailed theoretical study of the electronic, magnetic, and structural properties of magnesiowustite Fe-1 Mg-x(x) O with x in the range between 0 and 0.875 using a fully charge self-consistent implementation of the density functional theory plus dynamical mean-field theory method. In particular, we compute the electronic structure and phase stability of the rocksalt B1-structured (Fe,Mg) O at high pressures relevant for the Earths lower mantle. We find that upon compression paramagnetic (Fe,Mg) O exhibits a spin-state transition of Fe2+ ions from a high-spin to low-spin (HS-LS) state which is accompanied by a collapse of local magnetic moments. The HS-LS transition results in a substantial drop in the lattice volume by about 4%-8%, implying a complex interplay between electronic and lattice degrees of freedom. Our results reveal a strong sensitivity of the calculated transition pressure P-tr. upon addition of Mg. While, for Fe-rich magnesiowustite with Mg x amp;lt; 0.5, Ptr. is about 80 GPa, for Mg x = 0.75 it drops to 52 GPa, i. e., by 35%. This behavior is accompanied by a substantial change in the spin transition range from 50 to 140 GPa in FeO to 30 to 90 GPa for x = 0.75. In addition, the calculated bulk modulus (in the HS state) is found to increase by similar to 12% from 142 GPa in FeO to 159 GPa in (Fe,Mg) O with Mg x = 0.875. We find that the pressure-induced HS-LS transition has different consequences for the electronic properties of the Fe-rich and -poor (Fe,Mg) O. For the Fe-rich (Fe,Mg) O, the transition is found to be accompanied by a Mott insulator to a (semi) metal phase transition. In contrast to that, for x amp;gt; 0.25, (Fe,Mg) O remains insulating up to the highest studied pressures, implying a Mott-insulator to band-insulator phase transition at the HS-LS transformation.
Ämnesord
- NATURVETENSKAP -- Fysik -- Den kondenserade materiens fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Condensed Matter Physics (hsv//eng)
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