Site selection NMR study on electronic state in and near vortex core of YBa2Cu4O8 Original Research Article

We report a site-selective 17O spin–lattice relaxation rate T1−1 in the vortex state of YBa2Cu4O8. We found that T1−1 at the planar sites exhibits an unusual nonmonotonic NMR frequency dependence. Based on T1−1 in the vortex core region, we establish strong evidence that the local density of states within the vortex core is strongly reduced.