High-Frequency Properties of Y-Ba-Cu-O Josephson Junctions Fabricated with Helium Ion Beam Irradiation

We have fabricated spiral THz antennas containing embedded high $\mathrm{T}_{\mathrm{C}}\mathrm{YBa}_{2}\mathrm{Cu}_{3}\mathrm{O}_{7}$ (YBCO) focused helium ion beam Josephson junctions (JJ) for characterization of their high frequency characteristics. The values of the resistance and critical current of the junctions are controlled through the irradiation dose and geometry of the junction. We observe several orders of Shapiro steps in the current voltage characteristics of the device when irradiated with 0.6 THz and a single step when irradiated at 2.52 THz.