NONLINEAR SUSCEPTIBILITY - A DIRECT TEST OF THE QUADRUPOLAR KONDO EFFECT IN UBE13

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 Γ3(5f2) and Kramers (5f3) doublets. We find that nonlinear susceptibility measurements on single-crystal UBe13 are inconsistent with a quadrupolar (5f2) ground state of the uranium ion; the experimental data indicate that the low-lying magnetic excitations of UBe13 are predominately dipolar in character. © 1994 The American Physical Society.