High Q coplanar transmission line resonator of YBa2Cu3O7−x on MgO

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Abstract
We present the first coplanar waveguide transmission line resonator patterned from a perovskite high Tc superconducting film at 9 GHz. At 77 K the unloaded quality factor Q0 of the resonator patterned from a YBa2Cu3O7−x film on a MgO substrate is 1300, that is, 14 times higher than that of the copper resonator and 17 times higher than that of the gold resonator at the same temperature. At 4.2 K a Q0 factor of 3300 was measured for the YBa2Cu3O7−x /MgO resonator. Simple calculations of the quality factor show that values of 10 000 at 77 K should be possible using better substrates, films, and etching techniques. This resonator could form the basic structure of more complex microwave filter systems operating at liquid‐nitrogen temperatures.