Quantum Phenomenology for Heavy-Fermion Systems. I. Formulation of the Duality Model

Abstract

A quantum mechanical phenomenology for heavy-fermion systems is formulated. The effective Lagrangian for low-energy excitations contains a localized spin-fluctuation part which is coupled with an itinerant fermion part. Each part represents the dual nature of strongly correlated f electrons. The coupling parameter is fixed by comparison with the Fermi-liquid theory for the Anderson model. The comparison also fixes the localized spin-fluctuation spectrum. As an advantage over the Fermi-liquid description the present model takes into account the RKKY interaction and non-linear effects of spin polarization. A formula for the magnetic equation of state is derived which is applicable to the metamagnetism and weak antiferromagnetism in heavy-fermion systems.