Microwave noise emission from high T c thin films

Abstract
A pronounced X‐band microwave noise emission from Y‐Ba‐Cu‐O thin films has been observed. Emission depends strongly on temperture, bias current, and magnetic field. Two types of emission lines can be distinguished in the power versus dc bias spectra. The lines which remain at stable current positions against temperature we tentatively ascribe to the interaction of depinned flux flow with a two‐dimensional Josephson junction array. The lines that appear at fixed voltage positions may be attributed to the Josephson radiation of a distributed network of junctions. No significant emission was detected from Bi‐Ca‐Sr‐Cu‐O films.