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

Abstract

11B NMR measurements have been performed on a single crystal of YNi2B2C superconductor to investigate the vortex structure and dynamics. Below Tc, the 11B NMR spectrum, shift, linewidth, and transverse relaxation rate 1/T2 exhibit distinct features from which three vortex phases are identified, namely, vortex liquid, glass, and lattice. Also, thermal hysteresis of the saddle-point field, motional narrowing of linewidth, and double-peak structure of 1/T2 altogether indicate significant thermal motion of vortices in this low Tc and nearly isotropic three-dimensional superconductor. ?2000 The American Physical Society.