CONTROLLABLE ALTERATION OF THE PINNING ENERGY IN TL2CA2BACU2O8 FILMS BY PROTON IRRADIATION

Irradiation with 2 MeV protons increases the vortex pinning energy in Tl2Ca2BaCu2O8 films. The maximum pinning energy occurs at a defect den sity that depends on (1) the density of flux pinning centers in the un irradiated film, (2) the ratio of pinning energies of the pre- and pos t-irradiation defects, and (3) the effectiveness of the incident parti cle in creating pinning centers. An explicit formula for the pinning e nergy as a function of fluence is proposed.