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Volumn 275, Issue 5300, 1997, Pages 654-657

Magnetic collapse in transition metal oxides at high pressure: Implications for the earth

Author keywords

[No Author keywords available]

Indexed keywords

METAL OXIDE;

EID: 0030621135     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.275.5300.654     Document Type: Article
Times cited : (319)

References (36)
  • 6
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    • note
    • We are not considering magnetic transitions involving ordering and disordering of spins as in a Néel transition, but rather electronic transitions that change the magnitudes of spin moments.
  • 9
    • 10844286945 scopus 로고
    • G. L. Krasko, Phys. Rev. B 36, 8565 (1987); O. K. Andersen et al., Physica B+C, 86-88 B+C, 249 (1977).
    • (1987) Phys. Rev. B , vol.36 , pp. 8565
    • Krasko, G.L.1
  • 10
    • 4244133083 scopus 로고
    • G. L. Krasko, Phys. Rev. B 36, 8565 (1987); O. K. Andersen et al., Physica B+C, 86-88 B+C, 249 (1977).
    • (1977) Physica B+C , vol.86-88 B-C , pp. 249
    • Andersen, O.K.1
  • 12
    • 15644363526 scopus 로고    scopus 로고
    • note
    • We used density functional theory (DFT) methods, which are first principles in that they require no experimental input other than the nuclear charges and positions. LMTO-atomic sphere approximation (ASA) is a fast method that neglects nonspherical contributions to the potential. The LAPW method is among the most accurate electronic structure methods that assume no shape approximations. We compared LMTO-ASA results for CoO and FeO in the LDA approximation with the full-potential LAPW method and found satisfactory agreement. Equations of state are practically the same. The energy differences between high-and low-spin configurations had an error of tens of millirydbergs compared with LAPW, and LMTO transition pressures were about 20 GPa different from LAPW. We found no sensitivity to the number of k points (reciprocal lattice points used in Brillouin zone integrals), atomic sphere radii, or basis set sizes.
  • 14
    • 0028769664 scopus 로고
    • Collapse in B1 is above the structural transition into the B8 structure at high temperatures, although strained B1 can be maintained metastably to high pressures at room temperature [Y. Fei and H.-k. Mao, Science 266, 1678 (1994)].
    • (1994) Science , vol.266 , pp. 1678
    • Fei, Y.1    Mao, H.-K.2
  • 15
    • 0028604935 scopus 로고
    • Other available approaches would not be appropriate for this study. Hartree-Fock methods give excellent results for energetics in transition metal oxides at zero pressure but severely overestimate insulating gaps and are inapplicable for metals or for metal-insulator transitions. The B8 structure of FeO is metallic [X. Li and R. Jeanloz, Geophys. Res. Lett. 21, 2183 (1994)]. More exact methods such as GW [F. Aryasetiawan and O. Gunnarsson, Phys. Rev. Lett. 74, 3221 (1995)] are not tractable for the large number of structures and pressures necessary for this study.
    • (1994) Geophys. Res. Lett. , vol.21 , pp. 2183
    • Li, X.1    Jeanloz, R.2
  • 16
    • 11744384724 scopus 로고
    • Other available approaches would not be appropriate for this study. Hartree-Fock methods give excellent results for energetics in transition metal oxides at zero pressure but severely overestimate insulating gaps and are inapplicable for metals or for metal-insulator transitions. The B8 structure of FeO is metallic [X. Li and R. Jeanloz, Geophys. Res. Lett. 21, 2183 (1994)]. More exact methods such as GW [F. Aryasetiawan and O. Gunnarsson, Phys. Rev. Lett. 74, 3221 (1995)] are not tractable for the large number of structures and pressures necessary for this study.
    • (1995) Phys. Rev. Lett. , vol.74 , pp. 3221
    • Aryasetiawan, F.1    Gunnarsson, O.2
  • 18
    • 0005484511 scopus 로고
    • 3 [D.D. Sarma et al., Phys, Rev, Lett. 75, 1126, (1995)], because the transition metal hopping integrals are ∼40% larger than in binary oxides and the screened U is ∼40% smaller.
    • (1995) Phys, Rev, Lett. , vol.75 , pp. 1126
    • Sarma, D.D.1
  • 22
    • 15644371344 scopus 로고    scopus 로고
    • note
    • 3 was marginally unstable with respect to periclase plus stishovite.
  • 23
    • 0000124756 scopus 로고
    • C. B. Bargeron, M. Avinor, H. G. Drickamer, Inorg. Chem. 10, 1338 (1971); H. G. Drickamer and C. W. Frank, Electronic Transitions and the High Pressure Chemistry and Physics of Solids (Halsted, New York, 1973), pp. 126-129.
    • (1971) Inorg. Chem. , vol.10 , pp. 1338
    • Bargeron, C.B.1    Avinor, M.2    Drickamer, H.G.3
  • 25
    • 15644373676 scopus 로고    scopus 로고
    • note
    • mag = R In(M + 1 ), where R is the gas constant. For FeO, we estimate a bound of dP/oT < 0.015 GPa/K, which is close to the estimate of 0.01 GPa/K of Ohnishi (7). Thus, we expect an increase of about 29 GPa in transition pressure at 2000 K.
  • 35
    • 15644363565 scopus 로고    scopus 로고
    • note
    • 2g, from our computations.
  • 36
    • 15644375389 scopus 로고    scopus 로고
    • note
    • Supported by NSF grant EAR-9418934. Computations were performed on the Cray J90 at the Geophysical Laboratory. D.G.I, was supported in part by the U.S. Office of Naval Research and NSF grant EAR-9405965. We thank O. K. Andersen, Y. Fei, R. Hazen, R. Hemley, H. Krakauer, C. T. Prewitt, D. J. Singh, and L. Stixrude for helpful discussions.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.