LOW-TEMPERATURE SCANNING-TIP MICROWAVE NEAR-FIELD MICROSCOPY OF YBA2CU3O7-X FILMS

We have explored the low temperature capability of a scanning-tip micr owave near-field microscope to study superconductors. The shift in the quality factor of the microscope resonator can be used to obtain the temperature dependence of the surface resistance of a local region und er the tip. Patterned YBa2Cu3O7-x films were scanned at various temper atures and surface resistance mapping was performed with high spatial resolution at 1.2 GHz. Superconducting transitions at different positi ons on a film can be detected. Edge-region defects in wet-etched patte rns were observed and were shown to be nonsuperconducting at microwave frequencies at 80 K. (C) 1997 American Institute of Physics.