Non-Fermi Liquid and Fermi Liquid in Two-Channel Anderson Lattice Model: Theory for PrA₂Al₂₀ (A=V, Ti) and PrIr₂Zn₂₀

We theoretically investigate electronic states and physical properties in a two-channel Anderson lattice model to understand the non-Fermi liquid behaviors observed in PrV$_2$Al$_{20}$ and PrIr$_2$Zn$_{20}$ whose ground state of the crystalline electric field for local $f$-electron is the $\Gamma_3$ non-Kramers doublet of $f^2$-configuration and excited state is the $\Gamma_7$ Kramers doublet of $f^1$-configuration. We use the expansion from the limit of large degeneracy $N$ of the ground state ($1/N$-expansion), with $N$ being the spin-orbital degeneracy. Inclusion of the self-energy of the conduction electrons up to the order of $O(1/N)$ leads to heavy electron with channel and spin-orbit degeneracies. We find that the electrical resistivity is proportional to temperature $T$ in the limit of $T\to0$ and follows $\sqrt{T}$-law in the wide region of temperature, i.e., $T_x<T<T_0$, where typical values of $T_x$ and $T_0$ are $T_x\sim10^{-3}T_{\rm K}$ and $T_0\sim10^{-2}T_{\rm K}$, respectively, $T_{\rm K}$ being the Kondo temperature of the model. We also find non-Fermi liquid behaviors at $T\ll T_{\rm K}$ in a series of physical quantities; the chemical potential, the specific heat, and the magnetic susceptibility, explaining the non-Fermi liquid behaviors observed in PrV$_2$Al$_{20}$ and PrIr$_2$Zn$_{20}$. At the same time, we find that the Fermi liquid behavior becomes prominent for the system with smaller hybridization between $f$- and conduction electrons, explaining the Fermi liquid behaviors observed in PrTi$_2$Al$_{20}$.