Tl2Ba2CaCu2O8 films with very low microwave surface resistance up to 95 K

Abstract

Very low surface resistance Tl2Ba2CaCu2O8 films of thickness 1.0 μm on (100) LaAlO3 were fabricated and characterized. The films are highly c-axis oriented (x-ray diffraction rocking curve full width half maximum of 0.68°) with good in-plane epitaxy with respect to the substrate. The Tc of the films was 107.6±0.5 K as measured by ac magnetic susceptibility. The surface resistance at 10 GHz was measured with the parallel plate resonator technique and found to be 23±5 μΩ at 4.2 K, 130±20 μΩ at 77 K, and 300±60 μΩ at 95 K. Using a 20 GHz TE011 end-wall replacement copper cavity, the surface resistance was found to be comparable to that of copper, about 18 mΩ, at 104±1 K. The surface resistance of the films is significantly lower than that of all films reported to date at temperatures above 70 K and only slightly higher than the best high-temperature superconductor films reported to date at 4.2 K.

Fabrication, Structure and Properties of Tl-Based HTS Thin Films

“…Temperature (K) relationship, for TI-2212 and TI-2223 on LaAl03 are comparable with the best reported in the literature, 130J.J1l for 2212 [19] and less than 200J.J1l for 2223 [20,21]. These results also compare favourably with the best reported for YBCO, with an Rs of240Jill at 77K and 10GHz [22].…”

A Search for a Low Anisotropic Superconductor

“…When the transition metal ions are substituted at the Tl site in the charge reservoir layer of Tl-1223 superconductor the critical temperature was decreased following the same mechanism mentioned earlier [105]. The thin films of thallium based superconductors are of interest for electronic devices due to their higher T c (0) and low surface resistance R s [106]. Among the thallium-based compounds the thin films of single TlO layer materials (Tl-1223) are superior because of their higher T c (0) and J c [107].…”

The non-linear dynamics of vortices subjected to correlated and random pinning disorders in a quasi-2D superconductor

“…Details of preparation of Tl-2212 thin films on (100) LaAlO 3 substrates are described elsewhere [3]. We have used ∼ 1 µm thick films for the ac susceptibility measurements.…”