DISPLACEMENT DAMAGE IN SUPPORTED YBA2CU3O7-X THIN-FILMS AND FINITE-ELEMENT SIMULATIONS

The writing of Josephson weak links, in an electron microscope, onto f ilms of YBa2Cu3O7-x is an example of the high sensitivity of high-T-c superconductors to structural disorder and oxygen concentration. Radia tion damage occurs from electron beams with energy much less than the threshold normally required in compounds for knock-on of oxygen ions. Finite-element methods are used to simulate thermal and charge effects in the superconducting film and substrate. The calculations show that interstitials, under electric and thermal field gradients, drift away from the beam during damage and that diffusion-induced equilibrium is inhibited by the relatively rapid temperature fall after translating the beam.