Non-Fermi liquid normal state of the heavy-fermion superconductor UBe 13

Abstract

Non-Fermi liquid (NFL) behavior in the normal state of the heavy-fermion superconductor UBe 13 is studied by means of low-temperature measurements of the specific heat, C, and electrical resistivity, ρ, on a high-quality single crystal in magnetic fields up to 15.5 T. At B=0, unconventional superconductivity forms at T c=0.9 K out of an incoherent state, characterized by a large and strongly temperature dependent ρ( T). In the magnetic field interval 4 T⩽B⩽10 T , ρ( T) follows a T 3/2 behavior for T c( B)⩽ T⩽1 K, while ρ is proportional to T at higher temperatures. Corresponding non-Fermi liquid behavior is observed in C/ T as well and hints at a nearby antiferromagnetic (AF) quantum critical point (QCP) covered by the superconducting state. We speculate that the suppression of short-range AF correlations observed by thermal expansion and specific heat measurements below T L≈0.7 K ( B=0) yields a field-induced QCP, T L→0, at B=4.5 T.