Quantum criticality and the suppression of the heavy fermion state in UBe₁₃by high magnetic fields

Abstract

We have measured the electrical resistivity of a single crystal of UBe 13 below 1 K and in high magnetic fields to 33 T. The resistivity exhibits the T 2 dependence characteristic of a Fermi liquid at low temperatures. The field dependence of the coefficient of the T 2 term in the resistivity suggests that the heavy fermion state is suppressed by high magnetic fields. We discuss these results in light of a proposed field-induced quantum critical point immersed in the novel superconducting state of this compound.

Field-Orientation Dependence of Low-Energy Quasiparticle Excitations in the Heavy-Electron SuperconductorUBe13

“…The origin of NFL behaviors in UBe 13 remains unclear, and several possibilities have been discussed so far. These include quadrupolar Kondo effect with Γ 3 -crystalline-electric-field ground state for 5f 2 (U 4+ , J=4) configuration [19], an antiferromagnetic quantum-critical point induced by a magnetic field [17,20], and a competition between Kondo-Yosida and Γ 1 -crystallineelectric-field singlets for 5f 2 configuration [21]. Since the SC state apparently emerges out of the NFL state, its understanding is crucial in elucidating the pairing mechanism in UBe 13 .…”