Nonlinear Susceptibility: A Direct Test of the Quadrupolar Kondo Effect in UBe(13)

TL;DR

This paper uses nonlinear susceptibility measurements to test the quadrupolar Kondo effect in UBe13, finding that the experimental data do not support a quadrupolar 5f^2 ground state but suggest dipolar magnetic excitations.

Contribution

It provides a direct experimental test of the quadrupolar Kondo scenario in heavy fermion UBe13 using nonlinear susceptibility analysis.

Findings

Nonlinear susceptibility measurements are inconsistent with a quadrupolar 5f^2 ground state.

Experimental data indicate predominantly dipolar magnetic excitations.

The study challenges the quadrupolar Kondo interpretation for UBe13.

Abstract

We present the nonlinear susceptibility as a direct test of the quadrupolar Kondo scenario for heavy fermion behavior, and apply it to the case of cubic crystal-field symmetry. Within a single-ion model we compute the nonlinear susceptibility resulting from low-lying \Gamma_3 (5f^2 and Kramers (5f^3) doublets. We find that nonlinear susceptibility measurements on single-crystal UBe_{13} are inconsistent with a quadrupolar 5f^2 ground-state of the uranium ion; the experimental data indicate that the low-lying magnetic excitations of UBe_{13} are predominantly dipolar in character.