STM/STS studies of Bi–O layers of Pb doped Bi-2223 superconductors irradiated by 100 MeV oxygen ion

The effect of swift heavy ion (SHI) irradiation on the surface Bi–O layers of polycrystalline Pb doped Bi-2223 superconductors has been studied using Scanning Tunnelling Microscope (STM) technique. The STM images of the unirradiated Pb doped Bi-2223 samples show perfect periodicity of neighbouring atoms whereas the topographs of the irradiated samples reveal atomic displacements and disorder caused by SHI irradiation. The microstructures of these samples are found to be depth dependent. Studies of the electronic structure of the unirradiated and irradiated superconductors have been performed by Scanning Tunneling Spectroscopy (STS). These measurements show setting in of increased non-metallicity on the surface Bi–O layers as a result of irradiation.