Influences of zinc impurity on the zero bias conductance peak in [1 1 0] oriented optimally doped YBa2Cu3O7−x

We present a study of the influence of zinc impurities on the zero bias conductance peak (ZBCP) in tunnel junctions grown on [1 1 0] oriented optimally doped YBa2Cu3O7−x thin films. We report three specific results: (i) the ratio of the energy gap to the critical temperature remains constant; (ii) there is a weakening of the ZBCP; and (iii) the ZBCP field splitting is different from that in undoped YBCO, with a very small hysteresis and an overall field dependence incompatible with node removal.