Microwave-induced constant voltage steps in surface junctions ofBi2Sr2CaCu2O8+δsingle crystals

Abstract

We have observed the zero-crossing steps in a surface junction of a mesa structure micro-fabricated on the surface of a Bi-2212 single crystal. With the application of microwave of frequencies 76 and 94 GHz, the current-voltage characteristics show clear voltage steps satisfying the ac Josephson relation. Increasing the microwave power, the heights of the steps show the Bessel-function behavior up to step number n=4. We confirm that the intrinsic surface junction meets the criterion for the observation of zero-crossing steps.