B-11 NMR study of vortex dynamics in LuNi2B2C

Abstract

B-11 NMR measurements have been performed on single crystals of LuNi2B2C superconductor to investigate vortex lattice structure and dynamical behavior. The spectrum in the superconducting state is significantly broadened by local field inhomogeneity due to the vortex lattice and the peak point of the spectrum shifts toward low magnetic field due to the imperfect field penetration. The linewidth of the spectrum reflecting local field variation is much smaller than expected for conventional vortex lattices and shows a peculiar increase at low temperature. Furthermore, the transverse relaxation rate. 1/T-2 probing slow motion of vortices, exhibits a peak as temperature decreases. These results highlight significant fluctuation of vortices even for this low T-c and nearly isotropic 3D superconductor. (C) 2001 Elsevier Science BN. All rights reserved.