15N NMR studies of layered nitride superconductor LixZrNCl

NMR measurements were carried out on pristine ZrNCl and LixZrNCl. From the N-15-Knight shift study, the isotropic Knight shift, the traceless chemical (orbital) shift tensor and the traceless Knight shift tensor were determined as K-iso = -71 PPm. (sigma(1), sigma(2), sigma(3)) = (-55, -55, 110) ppm and (K-1, K-2, K-3) = (48, 48, -96) ppm, respectively. In the superconducting state, the fractional change of the N-15 NMR shift for H parallel to ab was observed, evidencing that the pairing symmetry is a spin-singlet state. (C) 2009 Elsevier B.V. All rights reserved.