NMR investigation of the quaternary-intermetallic-compound superconductorYNi2B2C

Measurements of the ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$ NMR spectrum, isotropic Knight shift (${\mathit{K}}_{\mathit{i}}$), and spin-lattice relaxation rate (1/${\mathit{T}}_1$) in an unoriented powder sample of ${\mathrm{YNi}}_2$ ${\mathrm{B}}_2$C are reported in the normal and the superconducting states. In the normal state, ${\mathit{K}}_{\mathit{i}}$ varies linearly from (+5.7±0.7) × ${10}^{\mathrm{-}4}$ at 300 K to (+4.9±0.7)×${10}^{\mathrm{-}4}$ just above the superconducting transition temperature. The anisotropic Knight shift, if present, is substantially smaller than ${\mathit{K}}_{\mathit{i}}$. An anomalous increase in (${\mathit{T}}_1$T${)}^{\mathrm{-}1}$ with decreasing temperature (T) is found in the normal state. From the behavior of the NMR linewidth in the superconducting state, the low-temperature limit λ(0)=(108±5) nm is found for the penetration depth. At the superconducting transition, 1/${\mathit{T}}_1$ drops rapidly and no Hebel-Slichter peak is seen.