Vortex dynamics in YNi2B2C single crystal by 11B NMR

B-11 pulsed nuclear magnetic resonance (NMR) measurements have been performed on a single crystal of YNi2B2C superconductor to investigate the vortex structure and dynamics. As temperature decreases, B-11 NMR. spectrum, shift, linewidth, and T-2(-1) exhibit distinct features, from which we are able to identify three vortex phases, namely, vortex liquid, vortex glass, and vortex lattice at 1.8T parallel to the c-axis. Also we has observed thermal hysteresis of saddle-point field, motional narrowing of linewidth and the double peak structures of T-2(-1), all of which indicate unexpectedly significant thermal motion of vortices in this low T-c and nealy isotropic 3D superconductor.