Supraleitung und Tieftemperaturtechnik. Thallium-HTSL-Mikrowellenbauelemente Abschlussbericht

Within the framework of the project 2'' Tl-HTS-films of Tl_2Ba_2Ca_2Cu_3O_x (2223)- and Tl_2Ba_2Ca_1Cu_2O_x (2212)-phase have been prepared on both sides of LaAlO_3-substrates by means of two-step technology. International peak values of the surface resistance R_s were reached for the Tl-2223-films [R_s (87 GHz, 77 K)=6.5 m#OMEGA#] and also for the Tl-2212-films [R_s (19 GHz, 77K)=490 #mu##OMEGA#], respectively. On basis of Tl-HTS/LaAlO_3-systems we have fabricated demonstrators of planar ring-resonator filters and dielectric HTS-resonators (for dielectric TE_1_1_1-filters) according to the filter-design layouts of the F.I.T./Bad Salzdetfurth. These demonstrators for the C-band have been chosen as preparations for n-pole input- and channel filters in IMUX-applications. On grounds of manufacture problems and rf-technical difficulties the dielectric filters were not successful. The planar filters show that it is possible to produce 2-pole filters with the exact specifications (f_0=4.000 GHz, #DELTA#f=17.5 MHz, S_2_1<-0.3 dB and S_1_1=-23 dB), but it very difficult to fabricate 8-pole filters. For the fabrication of 8-pole filters the selected filter principle (#lambda#-dual-mode ring resonators), the LaAlO_3-substrate and the Tl-2223-phase are not promising. These results and the demand of satellite communication for HTS-devices with high critical temperature resulted in the development of a preparation technology for Tl-2212-films on CeO_2-buffered saphire-substrates at the end of the project. Finally we could prepare 2''Tl-2212-films on buffered sapphire-substrates with R_s-values of about 300 #mu##OMEGA# by 5.6 GHz and 77 K. (orig.)SIGLEAvailable from TIB Hannover: F99B738+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Abscheidung von texturierten TIBaCaCuO-Schichten durch Sputtern

SIGLEAvailable from TIB Hannover: F94B0231+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

Grossflaechige Zweiseitenabscheidung von texturierten TlBaCaCuO-Schichten fuer Mikrowellenanwendungen Schlussbericht

Continuous improvement of the two step technology for preparation of Tl_2Ba_2Ca_2Cu_3O_x-films makes it possible to deposite large areas on LaAlO_3-substrates on both sides. The superconducting films were optimized with regard to low microwave losses and high power handling. Up to now the surface resistance at 77 K of our Tl-2223 films (R_S=6.5 m#OMEGA# at 87 GHz) is lower than the R_S-values of all measured HTS-films including the best YBCO-films. Furthermore we observed for the first time a decrease of the surface resistance below a temperature of 30 K for Tl-HTS films (R_S(87 GHz, 4.2 K)=1 m#OMEGA#). Such behaviour was only reported for high quality YBCO-films before. In cooperation with the industrial partners (R. Bosch GmbH and F.I.T. mbH) we have built up superconducting filters using Tl-HTS films, which will be later applied in IMUX-devices. This aim was pursued in two concepts for the C-band: (1) 3-, 5-and 7-pole microsrip filters with 2% and 10% bandwidth (2) dielectric TE_0_1_1-and TE_1_1_1-LaAlO_3-resonators with high unloaded quality factors (Q_o>5000). The F.I.T. mbH will use these resonators for the development of dielectric filters. At present not all problems with regard to the reproducibility of the resonator quality factors, the design accuracy and the mechanisms for the tuning of the filter characteristics are solved. Furthermore we have developed dielectric sapphire resonators with Q_o>2x10"6 at 5.6 GHz and 77 K using 2'' Tl-HTS films, which can act as high Q_o-resonators in the cryoradar systems. (orig.)Die Zweistufen-Technologie zur Herstellung der Tl_2Ba_2Ca_2Cu_3O_x-Schichten wurde so ausgebaut, dass eine grossflaechige und beidseitige Beschichtung auf hochfrequenztauglichen Substraten moeglich ist. Die Supraleiterschichten wurden hinsichtlich ihrer Mikrowellenverluste und Leistungsfestigkeit optimiert. An den Tl-2223 Schichten aus dem IPHT wurde der niedrigste Oberflaechenwiderstand [R_S (87 GHz, 77 K)=6,5 m#OMEGA#] aller bislang hergestelltn HTSL-Schichten gemessen. Erstmals wurde an diesen Tl-HTSL Schichten auch der bisher nur an sehr hochwertigen YBCO-Filmen gefundene R_S-Abfall zu tiefen Temperaturen hin beobachtet (R_S(87 GHz, 4.2 K)=1 m#OMEGA#). In Zusammenarbeit mit den Industriepartnern (R. Bosch GmbH und F.I.T. mbH) wurden supraleitende Filter auf der Basis von Tl-HTSL Schichten aufgebaut, die in IMUX-Demonstratoren eingesetzt werden sollen. Diese Aufgabe wurde in zwei Konzepten parallel fuer das C-Band verfolgt: (1) 3 bis 7-polige Mikrostreifenfilter mit 2 bzw. 10% Bandbreite (2) dielektrische TE_0_1_1- und TE_1_1_1-LaAlO_3-Resonatoren mit hohen Guetefaktoren (Q_o>5000). Mit diesen Resonatoren sollen dielektrische Kanalfilter bei der F.I.T./Bad Salzdetfurth entwickelt werden. Probleme gibt es noch bei der Reproduzierbarkeit der Resonatorgueten, der Designgenauigkeit und den Mechanismen fuer einen geeigneten Abgleich der Filtercharakteristiken. Ferner wurden dielektrische Saphir-Resonatoren mit Q_o>2x10"6 bei 5,6 GHz und 77 K auf der Basis von 2'' Tl-HTSL-Schichten aufgebaut, die als Hochguete-Resonatoren in der Kryo-Radartechnik eingesetzt werden koennen. (orig.)SIGLEAvailable from TIB Hannover: F96B1146+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Low-temperature quantum relaxation of single two-dimensional vortices in an epitaxial Tl2Ba2Ca2Cu3Ox thin film

Time-logarithmic magnetic-relaxation measurements have been obtained in an epitaxial Tl 2 Ba 2 Ca 2 Cu 3 O x thin film for the zero-field cooled and remanent magnetization, with low and moderate applied magnetic fields. With low fields ( H a =50 Oe), the normalized magnetic relaxation rates, S≡‖d(M/ M i )/d lnt‖, are temperature independent below T≃3.4 K, and the transition from the thermal to the quantum regime appears to be quite sharp. With moderate fields ( H a =500 Oe), the transition becomes smooth and takes place at temperatures higher than with low fields, T≃7 K. This seems to indicate that the mechanism responsible for low-temperature relaxation would be nondissipative Hall tunneling of two-dimensional vortices, rather than dissipative vortex motion

Technologische Grundlagen gesputterter Funktionsschichtsysteme fuer SQUID's und andere supraleitende Bauelemente Abschlussbericht

Available from TIB Hannover: FR 6969+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Low-temperature quantum relaxation of single two-dimensional vortices in an epitaxial Tl2Ba2Ca2Cu3Ox thin film

Time-logarithmic magnetic-relaxation measurements have been obtained in an epitaxial Tl 2 Ba 2 Ca 2 Cu 3 O x thin film for the zero-field cooled and remanent magnetization, with low and moderate applied magnetic fields. With low fields ( H a =50 Oe), the normalized magnetic relaxation rates, S≡‖d(M/ M i )/d lnt‖, are temperature independent below T≃3.4 K, and the transition from the thermal to the quantum regime appears to be quite sharp. With moderate fields ( H a =500 Oe), the transition becomes smooth and takes place at temperatures higher than with low fields, T≃7 K. This seems to indicate that the mechanism responsible for low-temperature relaxation would be nondissipative Hall tunneling of two-dimensional vortices, rather than dissipative vortex motion