Spiral growth pattern of high-Tc superconducting thin films by laser deposition

In-situ laser deposition was used to fabricate YBa2Cu3O7-x superconducting films on YSZ substrates. The surface topography of YBa2Cu3O7-x thin films has been studied with both atomic force microscopy (AFM) and scanning tunneling microscopy (STM). A stepped surface is clearly observed on the mounds with a single step edge the originates from a screw dislocation at the center of the mound and moves out to the edge in a spiral fashion. The experimental result show that the spiral growth structure is an intrinsic character of superconductor films. The existence or absence of the spiral growth structure and the quality of the spiral structures may have significant implications for properties of the high temperature superconducting thin films. The new visual details may lead to improvements of YBCO films.