VSM MEASUREMENTS OF CRITICAL CURRENTS FOR H-2-16+ LOW-ENERGY ION-IMPLANTED YBA2CU3O7-X THIN-FILMS( AND O)

A Vibrating Sample Magnetometer (VSM) was used to study the magnetic p roperties of YBa2Cu3O7-x (YBCO) thin films sputtered onto LaAlO3, SrTi O3 and MgO substrates, before and after ion implantation with deuteriu m and O-16+. By applying the Bean model, the irreversible magnetisatio n M, was converted into a critical current density J(c), using a lengt h scale A determined from a non-destructive technique, at each tempera ture. The implantation led to significant changes in the superconducti ng properties of the films. Most notably, for the deuterium implantati on in lower T(c) films (84K typically), T(c) was enhanced by several d egrees and M/LAMBDA was enhanced by 1.1 - 1.25 times. In higher T(c) f ilms (92K), T(c) and J(c) were unaltered at the present fluencies used . A similar observation was made for films with a range of T(c) values implanted with O-16+; when the T(c) was unaltered after implantation, M/LAMBDA was also unchanged, but where T(c) was depressed M/LAMBDA wa s enhanced by a factor of 2.3. Possible mechanisms are discussed.