Epitaxial Tl)2)Ba)2)Ca)2)Cu)3)O)10) films with very low microwave surface resistance up to 110K

• Published in: IEEE transactions on applied superconductivity Vol. 3; no. 1; pp. 1197 - 1200
• Main Authors: Holstein, W L, Parisi, L A, Wilker, C, Flippen, R B
• Format: Journal Article
• Language: English
• Published: 01-03-1993
• ISSN: 1051-8223
• DOI: 10.1109/77.233337

Very-low-surface-resistance epitaxial Tl)2)Ba)2)Ca)2)Cu)3)O)10) films have been prepared on one or both sides of (100) LaAlO)3) substrates up to 5 cm (2 in) in diameter. The critical temperature, < e1 > T < /e1 > )c), of the films was 120.5+/-0.5 K, as measured by AC magnetic susceptibility. Surface resistance at 10 GHz measured with a high-temperature-superconductor-sapphire resonator was 24+/-10 muOmega at 4.2 K, 181+/-10 muOmega at 77 K, and 359+/-20 muOmega at 100 K. Identical < e1 > T < /e1 > )c) and surface resistance were observed for films prepared on both sides of substrates. A microstrip resonator prepared from a double side-coated film on a LaAlO)3) substrate exhibited an unloaded < e1 > Q < /e1 > -value of 7200 at 100 K and 8.7 GHz and continued to demonstrate performance superior to similar copper resonators even at 115 K. This is the highest temperature reported to date for operation of a superconducting device