Microwave power handling in engineered $YBa2Cu3O7−δ$ grain boundaries Available to Purchase

Microwave-frequency (rf) power-dependence measurements performed on thin-film $YBa2Cu3O7−δ$ grain boundaries engineered on sapphire bicrystal substrates with misorientation angles of $θ=2°,$ $5°,$ $10°,$ and $24°$ are presented. The data are compared to measurements on films grown on single-crystal substrates. A stripline-resonator measurement technique is employed. The rf results are compared to dc measurements performed on a four-point test structure on the same substrate as the resonator. The measurements demonstrate that low-angle grain boundaries $(θ⩽10°)$ have little effect on the rf power handling, while the high-angle grain boundaries $(θ=24°)$ cause large nonlinear losses due to Josephson vortices created by rf currents.