Oxygen-isotope effects onLa0.65Ca0.35MnO3under pressure
| Autor: | Bernd Lorenz, Y.Y. Xue, Weimin Chen, C.W. Chu, A. K. Heilman, Jurgen P. Franck, Y. S. Wang |
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| Rok vydání: | 1999 |
| Předmět: | |
| Zdroj: | Physical Review B. 60:R14998-R15001 |
| ISSN: | 1095-3795 0163-1829 |
| Popis: | We have measured the O-isotope effects on the magnetic and electrical properties of ${\mathrm{La}}_{0.65}{\mathrm{Ca}}_{0.35}{\mathrm{MnO}}_{3}$ under hydrostatic pressure up to 1.9 GPa. The pressure was found to reversibly enhance the metal-insulator transition temperature ${T}_{C}$ and suppress the resistivity $\ensuremath{\rho}$ of both isotopic samples, but at different rates, depending on the O-isotopic mass of the samples. It was also found that pressure suppresses the isotope effect linearly, while the ${}^{18}{\stackrel{\ensuremath{\rightarrow}}{\mathrm{O}}}^{16}\mathrm{O}$ exchange drastically enhances $\ensuremath{\rho}.$ The greater $d\mathrm{ln}{T}_{C}/dP$ and $|d\mathrm{ln}\ensuremath{\rho}/dP|$ observed in the ${}^{18}\mathrm{O}$ sample can be understood qualitatively in terms of the double exchange interaction between Mn ions and the band reduction effect of polarons, but the $d\mathrm{ln}{T}_{C}/dP$ difference is much greater than predicted. The discrepancy suggests that modifications may be needed for the model. |
| Databáze: | OpenAIRE |
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