Magnetization, Maxwell's Relations and the Local Physics of the Dilute System Th_{1-x}U_{x}Ru_{2}Si_{2}

TL;DR

This study investigates the magnetic properties of the dilute Kondo compound Th_{1-x}U_{x}Ru_{2}Si_{2} using high-resolution magnetization measurements, revealing unconventional impurity behavior and challenging existing models of its quantum criticality.

Contribution

It provides new experimental insights into the impurity fixed point and the field dependence of the Fermi liquid temperature scale, questioning the applicability of the two-channel Kondo model.

Findings

T_F(H) increases linearly with magnetic field

Absence of zero-point entropy in the system

Field-magnetization as a probe for local impurity physics

Abstract

The dilute Kondo compound, Th_{1-x}U_{x}Ru_{2}Si_{2} (TURS), displays non-Fermi liquid behavior but no zero-point entropy; it thus appears to elude description by known single-ion models. It may also provide a clue to the underlying local degrees of freedom in its dense counterpart, URu_{2}Si_{2}. Here we use high-resolution magnetization studies to cross-check the thermodynamic consistency of previous experiments. Measurements of the field-dependence of the temperature-scale, T_F(H), associated with Fermi liquid behavior probes the nature of the underlying impurity fixed point. We find that T_F(H) grows linearly with applied field, in contrast to the quadratic form expected for the two-channel Kondo model. We use a scaling argument to show that the observed behavior of T_F(H) is consistent with the absence of zero-point entropy, suggesting novel impurity behavior in this material. More generally, we suggest the field-magnetization as a probe of single-ion physics and make predictions for its behavior in other actinide compounds.