Crystalline-Electric-Field Effect on the Resistivity of Ce-based Heavy Fermion Systems

The behavior of the resistivity of Ce-based heavy fermion systems is studied using a 1/N expansion method á la Nagoya, where N is the spin-orbital degeneracy of f-electrons. The 1/N -expansion is performed in terms of the auxiliary particles, and a strict requirement of the local constraints is fulfilled for each order of 1/N . The physical quantities can be calculated over the entire temperature range by solving the coupled Dyson equations for the Green functions self-consistently at each temperature. This 1/N -expansion method is known to provide asymptotically exact results for the behavior of physical quantities in both lowand high-energy regions when it is applied to a single orbital periodic Anderson model (PAM). On the basis of a generalized PAM including crystalline-electric-field splitting with a single conduction band, the pressure dependence of the resistivity ρ is calculated by parameterizing the effect of pressure as the variation of the hybridization parameter between the conduction electrons and f-electrons. The main result of the present study is that the double-peak structure of the T -dependence of ρ(T ) is shown to merge into a single-peak structure with increasing pressure.