Heavy-Ion Patterned Micro-Channels in YBCO Microwave Resonators

Microcollimated swift heavy-ion irradiation has been employed to carve channels with micron-sized width in YBa₂Cu₃O_7-x(YBCO) superconducting coplanar microwave resonators. Comparative analysis of the first two resonant modes as a function of temperature, magnetic field, and input power was used to characterize the properties of the microchannels. As expected, due to the high fluence, increase of penetration depth and microwave resistivity have been found in the irradiated channels. It is shown that the microchannels can be driven into a highly dissipative and nonlinear regime while the rest of the resonator still persists in a low-dissipation and linear state. Thus, an external control signal (e.g., a small dc magnetic field) can tune the response of the resonator, in the modes coupled to the microchannel, when properly biased. This study is preliminary to the employment of such approach in the design of novel YBCO sensors operating above 77 K.