Effective surface impedance of Y Ba₂Cu₃O_7−δfilms on silicon substrates

Abstract

We study the effect of the substrate on the effective surface impedance of a YBa 2 Cu 3 O 7−δ thin film grown over a silicon substrate. The microwave measurements, performed with a resonant cavity technique at two distinct frequencies (24 and 48 GHz), show anomalies both in the temperature and in the frequency dependences. By properly taking into account a relevant complex substrate contribution, with an important role played by the finite thickness effect, the whole set of data finds a satisfactory explanation in terms of standard impedance transformations. Using independent measurements at a single temperature, it is possible to extract the temperature dependence of the YBa 2 Cu 3 O 7−δ bulk surface impedance, which shows the expected frequency and temperature behaviours.

Robustness of the $0 -π$ transition against compositional and structural ageing in S/F/S heterostructures

“…The most direct information is given by Eq. ( 2): in fact, in thin structure of overall thickness d as ours, and not too close to T c , one has: 13,14…”

Cryogenic microwave wideband measurements of superconducting thin films

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