YBCO Thin Films for RF Applications

Thin films and crystals of YBa2Cu3O7-δ were exposed to 35 GHz microwave radiation and their nonlinear response was studied quantitatively by measuring the third-order harmonic signal at 105 GHz. Two extrinsic mechanisms are found to dominate the non-linear response: at low temperatures the presence of weak links, and at high temperatures close to Tc the RF induced flux line creation at film edges. Intrinsic nonlinearities are smaller by order of magnitudes at the RF current densities employed in this study (≤ 3.104 A/cm2) and are below the detection limit.