| Autor: |
Yang, J. B., Kim, M. S., Cai, Q., Zhou, X. D., Anderson, H. U., James, W. J., Yelon, W. B. |
| Zdroj: |
Journal of Applied Physics; 5/15/2005, Vol. 97 Issue 10, p10A312-1-10A312-3, 3p, 2 Charts, 2 Graphs |
| Abstrakt: |
We have studied the charge disproportionation phenomenon in CaFeO3 using the local-spin density approximation with the on-site Coulomb interaction parameter U and exchange parameter J. The calculation reveals that the total number of the 3d electrons is about 5.1 for both Fes1dsFe5+d and Fe(2)(Fe3+) atoms, and that there are about 0.25 electron holes in the O-2p band. Therefore, the charge disproportionation can be more accurately described as 2d5L(Fe4+)=d5L2(Fe5+)+d5(Fe3+), where L denotes a hole in the oxygen 2p band, instead of 2d4(Fe4+)=d3(Fe5+)+d5(Fe3+). The hybridization between the Fe-3d and O-2p orbitals is stronger for Fes1d than for Fe(2) due to the shorter Fe(1)-O bond. The hyperfine magnetic field contributed from conduction electron polarization is larger for Fe(2), resulting from a stronger s-d hybridization between the s orbital of Fe(2) and the d orbitals of its neighboring Fe(1) atoms. The on-site Coulomb repulsion and the exchange interaction increase the splitting between the occupied spin up and unoccupied spin down bands of Fe atoms. Fe-3d electrons become localized and the occupied d-band shifts to a lower energy range, even below the O-2p level. The calculated magnetic moments, hyperfine fields, and electron charge density agree well with the experimental data. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
|
