Effect of oxygen content on flux pinning in Nd-Ba-Cu-O single crystals

The magnetization of NdBa/sub 2/Cu/sub 3/O/sub y/ single crystals with various oxygen contents was investigated by superconducting quantum interference device (SQUID) magnetometer over a wide range of temperature and field. The results clearly indicate that the peak effect and flux pinning can be easily adjusted by changing the oxygen content in this material. Although the peak field decreases with increasing the amount of oxygen vacancies, J/sub c/ is significantly improved in the low fields and the peak effect becomes more pronounced. The oxygen vacancy clusters are very effective pinning centers and dominate the flux pinning in the sample subjected to the annealing and quenching process at 400/spl deg/C.