2003/06/03 by A. T. Holmes, D. Jaccard, K. Miyake +1 · 18 citations
Materials Science · Physics and Astronomy · #Iron-based superconductors research #Physics of Superconductivity and Magnetism #Rare-earth and actinide compounds #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.69.024508
published as Phys. Rev. B 69, 024508 (2004) · Submitted to Phys. Rev. B
arxiv created 2003/06/03 · openalex publication_date 2004/01/15 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
Simultaneous resistivity and ac specific heat measurements have been performed under pressure on single-crystalline 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, Tcmax. These anomalies can be linked with an abrupt change of the Ce valence and suggest a second quantum critical point at a pressure Pv\ensuremath≃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.