The effects of controlled point defects on the vortex-solid melting and depinning of high-temperature superconductors are investigated by applying the critical scaling analysis to the vortex transport properties of 3-MeV-proton-irradiated Y-Ba-Cu-O single crystals. For magnetic fields ranging from 1 kOe to 90 kOe, the critical exponents of the melting transition are found to be universal, independent of the density of point defects. In contrast, material parameters associated with the vortex depinning are modified by the proton irradiations.

• Received 14 December 1992

DOI:https://doi.org/10.1103/PhysRevB.47.8308