Crystal field levels and fine structure of the ground orbital state for high spin Fe2+ and Fe4+ ions in YBa2 (Cu1-x Fex )3 O7- δ
Authors:
- Czesław Zygmunt Rudowicz,
- Maolu Du,
- Yau-Yuen Yeung
Abstract
Crystal field energy levels within the whole 3d6 and 3d4 configuration and the fine structure of the ground orbital for high spin Fe2+ and Fe4+ ions at several possible sites in YBa2(Cu1-xFex)3O7- δ [YBCO] have been investigated. The calculations for three cases, namely 5D approximation, (5D and 3Γi) approximation and full diagonalization, show that the contribution to the splitting of the ground state due to spin-singlets (1Γi) is negligible but that due to spin-triplets (3Γi) is not negligible. Especially, in the case of Fe2+ in Cu(1) octahedral site, the spin-triplets contribution induces a change of the spin-ground state from Γ'4 to Γ'1. The dependence of the fine structure splittings on Fe concentration x in YBCO for Cu(1) octahedral and Cu(2) pyramidal sites is also investigated. The phase transition from orthorhombic to tetragonal structure at Fe concentration x ≊ 0.04 results in a degeneration of levels in the case of Fe2+ and Fe4+ in Cu(1) octahedral site at x > 0.04. In the case of Fe2+ and Fe4+ in Cu(2) pyramidal site a large variation of the ground state fine structure splittings is observed with increasing Fe concentration from low values to x = 0.04, but the splittings are almost constant at x greater than 0.04. The results corroborate our previous findings from the microscopic spin-Hamiltonian analysis within the 5D term on the large zero-field splitting for the Fe2+ and Fe4+ ions in YBCO. The present approach offers an improvement over the 5D approximation, which turns out to be inadequate for some ion/site cases because of strong contribution to the zero-field splitting due to the spin-triplet states. © 1993.
- Record ID
- UAM5a4ac67de59b4644a0c8276ee6b4046e
- Author
- Journal series
- Journal of Physics and Chemistry of Solids, ISSN 0022-3697
- Issue year
- 1993
- Vol
- 54
- Pages
- 733-744
- ASJC Classification
- ; ;
- DOI
- DOI:10.1016/0022-3697(93)90134-D Opening in a new tab
- Language
- (en) English
- Score (nominal)
- 0
- Score source
- journalList
- Publication indicators
- = 12; = 12; : 1999 = 0.848; : 2006 (2 years) = 1.164 - 2007 (5 years) =1.155
- Uniform Resource Identifier
- https://researchportal.amu.edu.pl/info/article/UAM5a4ac67de59b4644a0c8276ee6b4046e/
- URN
urn:amu-prod:UAM5a4ac67de59b4644a0c8276ee6b4046e
* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or PerishOpening in a new tab system.