MAGNETIC-FIELD INVESTIGATIONS OF SMALL SPUTTERED STEP-EDGE JUNCTIONS

YBa2Cu3O7 step-edge junctions are fabricated on SrTiO3-substrates. The steps of 300nm height are milled by argon-ion-beam-etching (IBE). The films are deposited by high-pressure on-axis magnetron sputter techni que patterned to microbridges with widths down to 0.5 mu m by electron beam lithography and argon ion etching. For ratios of film thickness to step height of t/h approximate to 1/2 the current-voltage character istics show Shapiro steps under microwave irradiation and RSJ-(resisti vely shunted junction)-like behavior. The periodic dependence of the c ritical current upon the magnetic field resembles a Fraunhofer-pattern . The period of the variation Delta B-0 follows a 1/w(2)-dependence in agreement with the theoretical prediction for planar thin Josephson j unctions: Delta B-0 = 1.84 phi(0)/w(2). Junctions with widths of 0.7 m u m possess a large magnetic field stability with Delta B-0 approximat e to 100G. Small junctions (w < 1 mu m) exhibit voltage jumps in the F raunhofer pattern, which are explained by flux penetration of single v ortices into the superconducting electrodes. The developed preparation technique for 'field-stable' Josephson junctions will be used for waf er scaling on 2-inch substrates and for the production of magnetically stable rf-SQUIDs.