Numerical Renormalization Group Study of non-Fermi-liquid State on Dilute Uranium Systems

TL;DR

This paper uses numerical renormalization group methods to study non-Fermi-liquid behavior in dilute uranium systems, revealing how crystal symmetry and specific impurity models explain anomalous electronic properties.

Contribution

It demonstrates the NFL behavior in the impurity Anderson model with a non-Kramers doublet, linking it to two-channel Kondo physics and experimental observations in uranium compounds.

Findings

NFL spectrum resembles two-channel Kondo model

Magnetic susceptibility shows -ln T divergence

Resistivity decreases with decreasing temperature

Abstract

We investigate the non-Fermi-liquid (NFL) behavior of the impurity Anderson model (IAM) with non-Kramers doublet ground state of the f$^2$ configuration under the tetragonal crystalline electric field (CEF). The low energy spectrum is explained by a combination of the NFL and the local-Fermi-liquid parts which are independent with each other. The NFL part of the spectrum has the same form to that of two-channel-Kondo model (TCKM). We have a parameter range that the IAM shows the $- \ln T$ divergence of the magnetic susceptibility together with the positive magneto resistance. We point out a possibility that the anomalous properties of U$_x$Th$_{1-x}$Ru$_2$Si$_2$ including the decreasing resistivity with decreasing temperature can be explained by the NFL scenario of the TCKM type. We also investigate an effect of the lowering of the crystal symmetry. It breaks the NFL behavior at around the temperature, $\delta /10$, where $\delta$ is the orthorhombic CEF splitting. The NFL behavior is still expected above the temperature, $\delta/10$.