Anomalous voltage modulation observed in YBCO dc-SQUIDs based on step-edge junctions

We have observed anomalous voltage vs. magnetic flux modulations in YBCO dc-SQUIDs employing step-edge junctions. The anomaly consists inphase inversion and frequency doubling of the voltage modulations in a restricted range of bias currents. We ascribe this phenomenon to the non-negligible capacitance of the junctions in the SQUID, as confirmed by numerical simulations.