Microwave properties of EuBa2Cu3O7−<i>x</i> thin films on MgO

Abstract

We have measured the microwave surface resistance of sputtered EuBa2Cu3O7−x superconducting films on MgO in a gold-plated Invar host cavity at 50 GHz. Low surface resistance of 2 mΩ was achieved even at 77 K and 50 GHz for highly c-axis oriented films with good in-plane epitaxy together with a Tc of 93 K and a Jc of 1.4×106 A/cm2 at 90 K. This surface resistance value is slightly lower than that for a classical superconductor of Nb at the same frequency at the same reduced temperature (T/Tc) of 7.7 K.