Electron-phonon interaction and the temperature dependence of elastic constants in heavy fermion systems

The electron-phonon interaction in the Periodic Anderson Model (PAM) to describe the temperature dependence of elastic constant in the heavy fermion (HF) systems has been studied. In order to understand the effect of electron-phonon coupling constant in these HF systems we couple the phonons to both the f-electrons band as well as to the hybridisation of f and conduction electron bands. The influence of various model parameters namely the position of 4f-level E0' the electron-phonon coupling strength f1(q) and f2(q), the effective coupling strength f12 (q)N(0)/ω(q) have been studied for the temperature dependence of elastic constant in HF systems. The results obtained are in good agreement with the general features observed experimentally for some HF systems. The results presented here are in the limit of U=0 and the numerical evaluations are made for q=0 and finite temperature. (author)