| Autor: |
Feyerherm, R., Dudzik, E., Prokes, K., Mydosh, J. A., Huang, Y. -K., Pöttgen, R. |
| Rok vydání: |
2014 |
| Předmět: |
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| Zdroj: |
Phys. Rev. B 90, 041104 (2014) |
| Druh dokumentu: |
Working Paper |
| DOI: |
10.1103/PhysRevB.90.041104 |
| Popis: |
CeRuSn exhibits an extraordinary room temperature structure at 300~K with coexistence of two types of Ce ions, namely trivalent Ce$^{3+}$ and intermediate valent Ce$^{(4-\delta)+}$, in a metallic environment. The ordered arrangement of these two Ce types on specific crystallographic sites results in a doubling of the unit cell along the $c$-axis with respect to the basic monoclinic CeCoAl-type structure. Below room temperature, structural modulation transitions with very broad hysteresis have been reported from measurements of various bulk properties. X-ray diffraction revealed that at low temperatures the doubling of the CeCoAl type structure is replaced by a different modulated ground state, approximating a near tripling of the basic CeCoAl cell. The transition is accompanied by a significant contraction of the $c$ axis. We present new x-ray absorption near-edge spectroscopy data at the Ce L$_{3}$ absorption edge, measured on a freshly cleaved surface of a CeRuSn single crystal. In contrast to a previous report, the new data exhibit small but significant variations as function of temperature that are consistent with a transition of a fraction of Ce$^{3+}$ ions to the intermediate valence state, analogous to the $\gamma \rightarrow \alpha$ transition in elemental cerium, when cooling through the structural transitions of CeRuSn. Such results in a valence-modulated state. |
| Databáze: |
arXiv |
| Externí odkaz: |
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