Effect of Magnetic Fields on Superconducting Microwave Coplanar Resonators

Coplanar microwave resonators made of NbN and YBa
₂
Cu
₃
O
_7-δ
show similar behavior under the influence of magnetic field. In particular, the two resonators exhibit marked difference between zero-field-cooled (ZFC) and field-cooled (FC) measurements, which is attributed to the presence of screening currents in ZFC but not in FC measurements.