Observation of proposed flux pinning sites in neutronhyphen;irradiated YBa2Cu3O7minus;x

摘要

Microstructure and magnetic hysteresis have been compared for two samples of the YBa2Cu3O7minus;dgr;(dgr;sim;0) highhyphen;temperature superconductor, one unirradiated, and one irradiated with fast neutrons (Egsim;0.1 MeV) to a fluence of 3times;1018n/cm2. Notable changes in the microstructure include strainhyphen;induced contrast from regions 2ndash;7 nm in size. An intrinsic critical current density (Jc) of 4.6times;106A/cm2in zero field at 4 K has been determined from magnetic hysteresis measurements for the irradiated sample while 1.2times;106A/cm2is noted for the unirradiated sample. We propose that the observed defect structure in the irradiated material is responsible for increased pinning and consequently higherJcrsquo;s.