Millimeter-Wave Surface Resistance of EuBa₂Cu₃O_7-y Film on MgO Substrates

Abstract

We have measured the surface resistance of c -axis-oriented EuBa 2 Cu 3 O 7- y thin films grown in situ onto (100)MgO by magnetron sputtering. The measurements were made at 50 GHz between 20 and 300 K in a TE 013 gold-plated invar cavity by replacing the endplate with a film. The surface resistance decreases sharply at 87 K to 40 m Ω at 77 K, becomes lower than that of an OFHC copper plate below 74 K, and lies within the measurement sensitivity range of 2 m Ω below 60 K. This low surface resistance suggests that MgO-based films are very suitable for high-frequency applications.