Zero-crossing steps in intrinsic Josephson junctions of Bi2Sr2CaCu2O8+δ

Abstract
We have investigated the response to microwave irradiation of small mesas fabricated on single crystals of Bi 2 Sr 2 CaCu 2 O 8+δ . We observe zero-crossing steps in the current-voltage characteristic which are consistent with the intrinsic Josephson junctions in the mesa stack phase-locking to the external microwave field.