Microscopic theory of Raman spectra of heavy fermion systems in the normal state

Abstract

In this communication, we develop the microscopic theory of Raman spectra of the heavy fermion (HF) system in its normal state at low temperatures. The system is described by the Periodic Anderson Model along with the coupling of the phonon to the bare f-electrons as well as to the hybridization between the conduction band and the f-electrons. The phonon Green's function and the phonon self-energy are evaluated by the equations of motion method of Zubarev. The phonon spectral density function (SDF) is evaluated at low temperatures in the long wavelength limit. The calculation depicts three Raman active modes one of which corresponds to the strongly renormalized phonon at the value of the reduced frequency ω ˜ ( = ω / ω 0 ) around 0.57 denoted as ( P 0 ), and the other two at low reduced frequencies of 0.08 ( P 1 ) and 0.025 ( P 2 ) in the SDF. The effect of electron–phonon (EP) coupling on Raman excitation peaks is investigated to probe the nature of the electronic states of the system.