Measurements and modeling of HTS shielded dielectric resonators

Abstract

We have performed accurate, reproducible and nondestructive measurements of the surface resistance of high quality YBazCu307, (YBCO) thin films in the temperature range 12 K to T, using a compact rutile dielectric resonator method at 9.6 GHz. The absolute values of the HTS surface resistance have been measured to systematic errors of less than 10 pQ at this frequency using this technique, which employ two resonator configurations with carefully chosen geometries. The resonators have unloaded Q factors of around lo5 at 77 K, increasing to above 5.105 below 15 K We have used three dimensional electromagnetic software ("Superfish") to study the effects of the copper shield on these rutile (TiOz) measurements, and others using lanthanum aluminate (LaA103) as the dielectric material. In the latter case, there are significant uncertainties (as large as 100%) in the measurements of the surface resistance of the YBCO films owing to the smaller field energy filling factor for LaAI03, since it has a lower relative permittivity than rutile.

Oxide-diluted magnetic semiconductors: a review of the experimental status

“…Epitaxial rutile films can also be obtained when using (111)-SrTiO 3 substrates [38]. Anatase TiO 2 is a wide bandgap semiconductor with excellent optical transmission in the visible and near-infrared regions, a high refractive index, high dielectric constant (ε R = 105 at 4.2 K) [39], low tangential loss (tan δ = 10 −7 at 4.2 K) [40] and useful photocatalysis properties [41].…”

Microstructure and magnetic properties of oxidized titanium nitride thin filmsin situgrown by pulsed laser deposition

“…Titanium dioxide (TiO 2 ) thin films have been studied and used extensively [1][2][3][4][5][6] since they possess remarkable optical, electronic, chemical and mechanical properties such as excellent optical transmittance (>85%) in the visible and near infrared wavelength ranges, high index of refraction (n ≈ 2.35 at 550 nm), large dielectric constant (ε r ≈ 105 at 4.2 K) and low loss tangent (tan δ ≈ 10 −7 at 4.2 K) [7,8], high chemical stability and mechanical durability. The widespread applications of TiO 2 films include (a) anti-reflecting and protective coating on optical elements; (b) capacitors or gates in microelectronic devices; (c) photocatalyst and catalytic devices; (d) optical waveguide in integrated optics and (e) suitable template layers for growing high-T c superconducting YBa 2 Cu 3 O 7 (YBCO) films, CrO 2 and LaSrMnO 3 films for microwave, biepitaxial junctions and spintronics applications [9][10][11].…”

Accuracy issues in surface resistance measurements of high temperature superconductors using dielectric resonators

“…An accurate technique yields the "correct" value for the parameter of interest, in this case, Rs. The dielectric resonator can be designed to meet these requirements and has become the de facto standard characterisation technique to measure the Rs of HTS samples [2]- [18].…”