MICROWAVE PROPERTIES OF YBA2CU3O7-X FILMS AT 35 GHZ FROM MAGNETOTRANSMISSION AND MAGNETOREFLECTION MEASUREMENTS

Microwave transmission and reflection measurements are performed simul taneously on thin films (approximately 1800 angstrom) of YBa2Cu3O7-x h aving their c axis perpendicular to the LaAlO3 substrate. We determine power transmission and reflection fractions, T(T, H) and R(T, H), as functions of temperature and static magnetic field (0 < H < 5.4 T), th e latter being applied perpendicular to the film. A guided-wave model, which we develop for our experimental situation, is the basis of a co mputational algorithm that extracts quantitative values of the complex penetration depth lambda, or alternatively the complex surface impeda nce Z(s), from T and R data. This inversion algorithm is successful wh en applied to test data generated from a phenomenological theory descr ibing the electrodynamic response of a type-II superconductor. The pro cedure is applied to T(T, H) and R(T, H) measurements to infer the tem perature- and field-dependent complex penetration depth lambda(T, H) t hat completely characterizes the superconductive film's electromagneti c response.