Phonon response of some heavy Fermion systems in dynamic limit

Abstract

The phonon excitation spectrum of some Heavy Fermion (HF) systems in the presence of electron–phonon interaction is studied in the dynamic limit ([Formula: see text]). The renormalized excitation phonon frequencies ([Formula: see text]) are evaluated through Periodic Anderson Model (PAM) in the presence of electron–phonon interaction using Zubarev-type double time temperature-dependent Green function. The calculated renormalized phonon energy is analyzed through the plots of ([Formula: see text]) against temperature for different system parameters like effective coupling strength ‘[Formula: see text]’ and the position of [Formula: see text]-level ‘[Formula: see text]’. The observed behavior is analyzed and found to agree with the general features of HF systems found in experiments. Further, it is observed that in finite but small [Formula: see text]-values the propagating phonons harden and change to localized peaks.