Document Detail

The role of equilibrium volume and magnetism on the stability of iron phases at high pressures.
MedLine Citation:
PMID:  24355938     Owner:  NLM     Status:  Publisher    
The present study provides new insights into the pressure dependence of magnetism by tracking the hybridization between crystal orbitals for pressures up to 600 GPa in the known hcp, bcc and fcc iron. The Birch-Murnaghan equation of state parameters are; bcc: V0 = 11.759 A(3)/atom, K0 = 177.72 GPa; hcp: V0 = 10.525 A(3)/atom, K0 = 295.16 GPa; and fcc: V0 = 10.682 A(3)/atom, K0 = 274.57 GPa. These parameters compare favorably with previous studies. Consistent with previous studies we find that the close-packed hcp and fcc phases are non-magnetic at pressures above 50 GPa and 60 GPa, respectively. The principal features of magnetism in iron are predicted to be invariant, at least up to ∼6% overextension of the equilibrium volume. Our results predict that magnetism for overextended fcc iron disappears via an intermediate spin state. This feature suggests that overextended lattices can be used to stabilize particular magnetic states. The analysis of the orbital hybridization shows that the magnetic bcc structure at high pressures is stabilized by splitting the majority and minority spin bands. The bcc phase is found to be magnetic at least up to 600 GPa; however, magnetism is insufficient to stabilize the bcc phase itself, at least at low temperatures. Finally, the analysis of the orbital contributions to the total energy provides evidence that non-magnetic hcp and fcc phases are likely more stable than bcc at core earth pressures.
S Alnemrat; J P Hooper; I Vasiliev; B Kiefer
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-12-20
Journal Detail:
Title:  Journal of physics. Condensed matter : an Institute of Physics journal     Volume:  26     ISSN:  1361-648X     ISO Abbreviation:  J Phys Condens Matter     Publication Date:  2013 Dec 
Date Detail:
Created Date:  2013-12-20     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101165248     Medline TA:  J Phys Condens Matter     Country:  -    
Other Details:
Languages:  ENG     Pagination:  046001     Citation Subset:  -    
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