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Pressure-induced enhancement of superconductivity and superconducting-superconducting transition in CaC$\_6$

Andrea Gauzzi·S. Takashima·N. Takeshita·C. Terakura·H. Takagi·N. Emery·C. Herold·P. Lagrange·G. Loupias
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Abstract

We measured the electrical resistivity, $\varrho(T)$, of superconducting CaC$\_6$ at ambient and high pressure up to 16 GPa. For $P \leq$8 GPa, we found a large increase of $T\_c$ with pressure from 11.5 up to 15.1 K. At 8 GPa, $T\_c$ drops and levels off at 5 K above 10 GPa. Correspondingly, the residual $\varrho$ increases by $\approx$ 200 times and the $\varrho(T)$ behavior becomes flat. The recovery of the pristine behavior after depressurization is suggestive of a phase transition at 8 GPa between two superconducting phases with good and bad metallic properties, the latter with a lower $T\_c$ and more static disorder.

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Andrea Gauzzi, S. Takashima, N. Takeshita, C. Terakura, H. Takagi, N. Emery, C. Herold, P. Lagrange, G. Loupias. 2006-03-16. Pressure-induced enhancement of superconductivity and superconducting-superconducting transition in CaC$\_6$. https://arxiv.org/abs/cond-mat/0603443

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