Vortex structure and dynamics in YNi2B2C single crystal by B-11 NMR

B-11 NMR measurements have been performed on a single crystal of YNi2B2C su perconductor to investigate the vortex structure and dynamics. Below T-c, t he B-11 NMR spectrum, shift, linewidth, and transverse relaxation rate 1/T- 2 exhibit distinct features from which three vortex phases are identified, namely, vortex liquid, glass, and lattice. Also, thermal hysteresis of the saddle-point held, motional narrowing of linewidth, and double-peak structu re of 1/T-2 altogether indicate significant thermal motion of vortices in t his low T-c and nearly isotropic three-dimensional superconductor.