ABSTRACT
During imaging by STM, we have observed surface modification of YBa2Cu3O7-δ high temperature superconducting thin films (grown by PLD) on single crystal (001) MgO and SrTiO3 substrates. Repeated scanning of the same area led to gradual removal of material from the edge of mesas and nucleation and growth of holes. Removal was not necessarily restricted to the top layer as etching occurred at all exposed surfaces. Scanning is finally interrupted by the influence of the insulating substrate. The absence of debris at the edge of the scanned area implies that the loss of material was due to electric field induced effects rather than milling.
