THE EFFECT OF DELIBERATELY INDUCED DISORDER ON THE ELECTRONIC-STRUCTURE OF THE BI-2212 HIGH T-C SUPERCONDUCTOR

We have irradiated by thermal neutrons single crystals of the Bi-2212 high T-c superconductor. The irradiated samples are insulators, but th ey regain high T-c superconductivity after an annealing in He at 450-5 50 degrees C. Depending on irradiation doses and annealing parameters, we obtained two insulators, with more or less disorder, and two super conductors with different values of T-c. We performed resistivity, a.c . susceptibility and angle resolved photoemission studies (ARPES). The coherent quasiparticle intensity in the vicinity of the chemical pote ntial is considerably reduced in the insulating samples along both the Gamma-M and Gamma-Y high symmetry directions. It is recovered once th e superconductivity is reestablished, and develops together with T-c a long the Cu-O bond (Gamma-M) direction.