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

TL;DR

This paper investigates how crystalline-electric-field effects influence the resistivity of Ce-based heavy fermion systems, revealing that pressure causes a merging of the resistivity's double-peak into a single peak, using a 1/N-expansion approach.

Contribution

It introduces a generalized periodic Anderson model including crystalline-electric-field splitting and applies a 1/N-expansion to analyze resistivity under pressure effects.

Findings

Resistivity exhibits a double-peak structure at low pressure.

Increasing pressure causes the double-peak to merge into a single peak.

The model accurately captures the pressure dependence of resistivity.

Abstract

The behavior of the resistivity of Ce-based heavy fermion systems is studied using a 1/$N$-expansion method a 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 low- and 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 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 the resistivity is shown to merge into a single-peak structure with increasing pressure.