EFFECTIVE PINNING POTENTIAL IN PB-DOPED HG-1234 SUPERCONDUCTOR BY AC SUSCEPTIBILITY RESPONSE

From the TEM microanalysis, there is presence of intergrowth structure s in our Pb-doped Hg-1234 superconductor. By using the ac susceptibili ty measurements, the temperature, current density, and magnetic field dependence of the effective pinning potential U(T,H,J) for our Pb-dope d Hg-1234 superconductor has been determined. It is found that, the cu rrent density dependence of U(T,H,J) obeys the inverse power law of th e collective pinning theory. Moreover, as the current density J increa ses, the effective pinning potential of our Pb-doped specimen is dropp ed much faster than that of HgBa2Ca2Cu3O8+delta one. It is found that the intergrowth structures in our specimen act as weak pinning centres .