Hu, Z. ; Grazioli, C. ; Knupfer, M. ; Golden, M. S. ; Fink, J. ; Mahadevan, Priya ; Kumar, Ashwani ; Ray, Sugata ; Sarma, D. D. ; Warda, S. A. ; Reinen, D. ; Kawasaki, S. ; Takano, M. ; Schüssler-Langeheine, C. ; Mazumdar, Chandan ; Kaindl, G. (2002) Difference in spin state and covalence between La1−xSrxCoO3 and La2−xSrxLi0.5Co0.5O4 Journal of Alloys and Compounds, 343 (1-2). pp. 5-13. ISSN 0925-8388
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Official URL: http://www.sciencedirect.com/science/article/pii/S...
Related URL: http://dx.doi.org/10.1016/S0925-8388(02)00004-X
Abstract
We present a comparative study of the spin states and electronic properties of La1−xSrxCoO3 and La2−xSrxLi0.5Co0.5O4 using X-ray absorption near-edge structure spectroscopy at both the O-K and Co-L2,3 thresholds. In the La2−xSrxLi0.5Co0.5O4 system the CoO6 octahedra are isolated, the holes induced by Sr doping are trapped in the isolated Co(IV)O6 octahedra, and a low-spin state is found for the Co ions, which does not change upon Sr doping. In the La1−xSrxCoO3 system, the interconnected CoO6 octahedra, with a 180° Co-O-Co bond angle, give rise to a transition from low-spin to intermediate-spin state with a ferromagnetic alignment of the Co spins. The double-exchange, ferromagnetic coupling between Co ions mediated by the 180° bond angle is responsible for suppressing the low spin-state. We find that the branching ratio of spectral intensities at the L2 and L3 thresholds in the Co-L2,3 X-ray absorption spectra is sensitive to the spin state of the Co ions allowing its direct spectroscopic determination.
| Item Type: | Article |
|---|---|
| Source: | Copyright of this article belongs to Elsevier Science. |
| Keywords: | Rare Earth Compounds; Transition Metal Compounds; X-ray Spectroscopy; Magnetic Properties; Electronic Properties |
| ID Code: | 46438 |
| Deposited On: | 04 Jul 2011 11:55 |
| Last Modified: | 04 Jul 2011 11:55 |
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