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.
@article{arxiv.cond-mat/9405072,
title = {Nonlinear Susceptibility: A Direct Test of the Quadrupolar Kondo Effect in UBe(13)},
author = {A. P. Ramirez and P. Chandra and P. Coleman and Z. Fisk and J. L. Smith and H. R. Ott},
journal= {arXiv preprint arXiv:cond-mat/9405072},
year = {2009}
}