Nuclear magnetic resonance and heavy-fermion superconductivity in (U, Th)Be13

Be9 NMR and relaxation have been used to probe heavy-fermion superconductivity in U1-xThxBe13, x=0 and 0.033. The spin-lattice relaxation rate 1T1 varies approximately as T3 well below the transition temperature. This is consistent with a class of anisotropic pairing models for which the gap vanishes along lines on the Fermi surface. NMR spectra give no indication of magnetic, structural, or charge-density ordering at a second transition for x=0.033. © 1984 The American Physical Society