Observation of Shapiro-Steps in AFM-Plough Micron-Size YBCO Planar Constrictions

Using an atomic force microscope (AFM), we successfully ploughed micron size planar constriction type junctions on YBa₂Cu₃O_7-x thin films. The 100 nanometer (nm) thin films are deposited on MgO substrates by an inverted cylindrical magnetron (ICM) sputtering technique. The films are then patterned into 8-10 micron size strips, using photolithography and dry etching. A diamond coated tip was used with the AFM in this process. We were able to observe well defined current-voltage (I-V) characteristics and Shapiro-steps, successfully demonstrating a possible Josephson effect in these constrictions.