| We consider a three-dimensional, Extended Periodic Anderson Model (EPAM) with non-local hybridisation, Vfc, between the localised f electrons and wideband conduction (c) electrons. The model is supplemented by a direct coulomb interaction, Ufc, and solved in the Uff=∞ limit. Remarkably,a quantum phase transition (QPT) associated with f-valence fluctuations is found to separate the heavy FL from the AF ordered phase as Vfc is tuned across a critical value. This is accompanied by a discontinuous jump in the Fermi volume across the QCP. An unconventional superconductive instability, driven by these extended, singular valence fluctuations, naturally emerges. {\it All} these phenomena are representative of observations in pressurized CeCu2Si2. |
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