Soldering and Peeling Commercial REBCO Tapes for Microwave Resonant Cavity

Searching for dark matter is among the most ambitious research fields aimed at a deep understanding of the universe. Axions are candidate particles supposed to be a relevant component of cold dark matter. They can be detected through high-quality factor (Q) resonant microwave cavities named haloscopes. In order to reach high Q factor, conventional copper cavities can be coated with a superconducting layer. Materials with high irreversibility field such as rare-earth barium cuprates (REBCO) are able to increase the figure of merit B2Q of bare copper cavity at 4.2 K by an order of magnitude over a field range 3–10 T at 9 GHz and in the frequency range 1–100 GHz at 5 T. A simple way to obtain a coated resonator is soldering high-quality commercial REBCO tapes on a sector-shaped cavity. In this contribution, we tested the effect of a two-step method, which includes soldering and peeling, on the structural, morphological and superconducting properties of REBCO layer to be adopted for resonant cavity inner coating. Several REBCO tapes obtained from different producers were tested. Morphological and compositional analyses indicate that different tapes show a different behaviour as a consequence of the peeling process. Soldering and peeling tests point out that REBCO-buffer layer interface is critical to obtain a sector cavity with uniformly exposed REBCO film.