Millimeter and submillimeter wave surface impedance of YBa2Cu3O7−δ thin films with reduced low temperature absorption

✍ Scribed by N. Klein; U. Dähne; U. Poppe; H. Soltner; B. Kabius; K. Urban; J. Schubert; W. Zander; S. Orbach; S. Hensen; G. Müller; H. Piel; B.P. Gorshunov; G.V. Kozlov; S.P. Lebedev; A.A. Volkov

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 272 KB
• Volume: 185-189
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(91)91014-u

✦ Synopsis

The surface impedance of epitaxiai YBa~CuaOT_ ~ thin films prepared by high oxygen pressure dc sputtering as well as by excimer laser ablation on ISaAIO 3 has been measured at 87GHz by a cavity endplate replacement technique and between 100GHz and 1THz by transmission experiments, some of our films with low dcresistivity values (p(100K)=40-S0t~t~cm, p(300K)Ip(100K} >3} and improved microstructure exhibit besides the initial steep falloff at T c a further gradual decrease of the surface resistance below about 50K by at least one order of magnitude, presently limited by the sensitivity of our measurement techniques. The dynamic conductivity determined from the surface impedance shows a maximum below T~ looking similar to a BCS coherence peak. Beyond the relevance for the understanding of the conduction me'chanism our low loss films are important for millimeter-and submillimeter wave applications below Tc/2.