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Signatures of valence fluctuations in CeCu2Si2 under high pressure

Miyake, Kazumasa
Published in Physical Review. B, Condensed Matter. 2004, vol. 69, no. 2
Abstract Simultaneous resistivity and ac specific heat measurements have been performed under pressure on singlecrystalline CeCu2Si2 to over 6 GPa in a hydrostatic helium pressure medium. A series of anomalies was observed around the pressure coinciding with a maximum in the superconducting critical temperature, Tc max . These anomalies can be linked with an abrupt change of the Ce valence and suggest a second quantum critical point at a pressure Pv.4.5 GPa, where critical valence fluctuations provide the superconducting pairing mechanism, as opposed to spin fluctuations at ambient pressure. Such a valence instability—and associated superconductivity—is predicted by an extended Anderson lattice model with Coulomb repulsion between the conduction and f electrons. We explain the T-linear resistivity found at Pv in this picture, while other anomalies found around Pv can be qualitatively understood using the same model
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Research group Groupe Triscone
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HOLMES, Alexander, JACCARD, Didier, MIYAKE, Kazumasa. Signatures of valence fluctuations in CeCu2Si2 under high pressure. In: Physical Review. B, Condensed Matter, 2004, vol. 69, n° 2. doi: 10.1103/PhysRevB.69.024508 https://archive-ouverte.unige.ch/unige:35761

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Deposited on : 2014-04-15

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