Landau Fermi-liquid theory for heavy-fermion compounds .2. Collective modes

We generalize the Landau Fermi-liquid theory for describing kinetic phenomena in heavy-fermion compounds at low temperatures. The kinetic equation is derived and solved for the case when collisions between quasi-particles are negligible. Collective zero-sound and spin-wave modes are studied. We found that zero-sound modes are broken down by phase fluctuations. Symmetric collective spin excitations consist of acoustic-like and optical-like modes. The former excitations are decaying, whereas the latter excitations are stable. Electron spin resonance is also investigated. It is found that localized f electrons give the main contribution to the resonance and determine the resonance frequency. The usual Landau parameters F-0(s) and F-0(a) for heavy-fermion systems are determined.