| Autor: |
Gauzzi, A., Bendiab, N., D΄Astuto, M., Canny, B., Calandra, M., Mauri, F., Loupias, G., Takashima, S., Takagi, H., Takeshita, N., Terakura, C., Emery, N., Herold, C., Lagrange, PH., Hanfland, M., Mezouar, M. |
| Zdroj: |
High-pressure Crystallography; 2010, p407-418, 12p |
| Abstrakt: |
Superconducting CaC6 is found to exhibit two important pressure effects: (i) a large P-induced Tc enhancement up to 15.1 K at 7.5 GPa, the highest Tc value hitherto reported for graphite intercalated compounds; and (ii) a dramatic Tc drop down to ~3 K at a critical pressure of ~9 GPa suggestive of a structural instability. We show that a combined electrical resistivity and x-ray diffraction study under high pressures provides a comprehensive account of both phenomena within the frame of the BCS theory in terms of a P-induced softening of the in-plane Ca mode relevant to the electron–phonon coupling. Our data analysis indicates that, below ~8 GPa, the softening contributes to the Tc enhancement whilst, at higher pressures, it drives the system to a disordered phase presumably characterized by a disordering of the Ca sublattice. Thus, pressure induces a simultaneous order-disorder and lattice-softening phase transition from a good metal phase with high Tc to a bad metal phase with low Tc. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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