Theory of the thermoelectricity of intermetallic compounds with Ce or Yb ions

TL;DR

This paper models the thermoelectric properties of Ce and Yb intermetallic compounds using the Anderson model, successfully explaining experimental thermopower features and pressure effects through a detailed theoretical approach.

Contribution

It introduces a comprehensive Anderson model analysis that accounts for crystal-field splitting and Coulomb repulsion, accurately reproducing thermoelectric behavior and phase diagrams of Ce and Yb intermetallics.

Findings

Thermopower features match experimental observations.

Pressure influences energy scales and phase transitions.

Model explains temperature, pressure, and doping effects on transport properties.

Abstract

The thermoelectric properties of intermetallic compounds with Ce or Yb ions are explained by the single-impurity Anderson model which takes into account the crystal-field splitting of the 4{\it f} ground-state multiplet, and assumes a strong Coulomb repulsion which restricts the number of {\it f} electrons or {\it f} holes to $n_f\leq 1$ for Ce and $n_f^{hole}\leq 1$ for Yb ions. Using the non-crossing approximation and imposing the charge neutrality constraint on the local scattering problem at each temperature and pressure, the excitation spectrum and the transport coefficients of the model are obtained. The thermopower calculated in such a way exhibits all the characteristic features observed in Ce and Yb intermetallics. Calculating the effect of pressure on various characteristic energy scales of the model, we obtain the $(T,p)$ phase diagram which agrees with the experimental data on CeRu$_{2}$Si$_2$, CeCu$_{2}$Si$_2$, CePd$_{2}$Si$_2$, and similar compounds. The evolution of the thermopower and the electrical resistance as a function of temperature, pressure or doping is explained in terms of the crossovers between various fixed points of the model and the redistribution of the single-particle spectral weight within the Fermi window.