NMR compared to band structure calculations of the quaternary superconductor La3Ni2B2N3−x

Abstract

We measured susceptibility and NMR spectra, spin-lattice, and spin-spin relaxation of ${}^{11}$B and ${}^{139}$La in the quaternary superconductor La${}_{3}$Ni${}_{2}$B${}_{2}$N${}_{3\ensuremath{-}x}$ and compare these experimental results to full potential density functional theory band structure calculations. The electric field gradients (EFGs) at B and La sites clearly show that the N vacancies are restricted to the N(2$b$) sublattice. Temperature-dependent susceptibility, Knight shift, and nuclear spin-lattice relaxation ${T}_{1}$ are successfully described within the Fermi-liquid model. The Hebel-Slichter peak is suppressed in the mixed state and in the presence of paramagnetic impurities.