DMFT Study for Valence Fluctuations in the Extended Periodic Anderson Model

We study valence fluctuations at finite temperatures in the extended periodic Anderson model, where the Coulomb interaction between conduction and localized $f$-electrons is taken into account, using dynamical mean-field theory combined with the continuous-time quantum Monte Carlo (CT-QMC) method. The valence transition with the hysteresis is clearly found, indicating the first-order phase transition between the Kondo and mixed-valence states. We demonstrate that spin correlation rapidly develops when the system approaches the valence transition point. The comparison of the impurity solvers, %: the CT-QMC, non-crossing approximation, and one-crossing approximation, is also addressed.