In this paper, we present a detailed investigation of the self-field transport properties of an ionic liquid gated ultra-thin YBa2Cu3O7−x (YBCO) film. From the high temperature dynamic of the resistivity (>220 K), different scenarios pertaining to the interaction between the liquid and the thin film are proposed. From the low temperature evolution of Jc and Tc, a comparison between the behavior of our system and the standard properties of YBCO is drawn.

In this paper the feasibility of Fe(Se,Te) Coated Conductors (CC) on simple Rolling-Assisted Biaxilly Textured Substrate (RABiTS) template is studied. Starting from commercially available NiW5% tapes from Evico which have an out-of-plane orientation of about 6° and an in-plane orientation of 5.3°, a RABiTS template for Fe(Se,Te) coated conductors was realized depositing CeO2 thin films on the metallic tape. The oxide buffer layers, deposited via Pulsed Laser Ablation, have an out-of-plane and an in-plane orientation suitable for Fe(Se,Te) deposition and act as a chemical barrier against Ni diffusion. The Fe(Se,Te) deposited on such a simple template show a superconducting transition Tc of 18 K, very high upper critical field values with a Tc,0 of only 3 K in 18 T and self-field transport isotropic critical current values of 10 5 A/cm 2 at 4.2 K, which is reduced of less than one order of magnitude up to 16 T.

The introduction of artificial pinning sites in YBa2 Cu3O7−d (YBCO) epitaxial thin films has been\ud obtained by pulsed laser deposition ͑PLD͒ technique from YBCO-BaZrO3 ͑BZO͒ composite targets\ud with BZO concentration ranging from 2.5 to 7 mol %. The typical critical temperature, Tc , drop\ud observed in YBCO-secondary phase films grown by PLD has been successfully recovered by\ud increasing the deposition temperature. Transport properties analyses revealed improved pinning\ud force values for YBCO-BZO films for BZO concentration above 5 mol %. These films exhibited an\ud anomalous dual peak structure which has been ascribed to the presence of two pinning\ud contributions. The crossover field, Bm , separating these two pinning regimes has been observed to\ud be temperature independent suggesting the occurrence of the matching field effect. The measured\ud value of Bm agreed with the matching field value, B⌽ = Knd⌽0 , as evaluated from transmission\ud electron microscopy investigations. The mark of this phenomenon is retained down to 10 K, making\ud YBCO-BZO more performing than pristine YBCO films at applied magnetic fields below Bm in all\ud the temperature range inspected. On the contrary, in the high magnetic field range ͑above Bm͒, the\ud effectiveness of correlated pinning is progressively reduced on lowering the temperature suggesting\ud that at low temperatures the dominant pinning contribution arises from isotropic pinning centers

We observe a strong reduction of the field induced thin film surface resistance measured at high microwave frequency (ν =47.7 GHz) in YBa2Cu3O 7−δ thin films grown on SrTiO3 substrates, as a consequence of the introduction of sub-micrometric BaZrO3 particles. The field increase of the surface resistance is smaller by a factor of ∼3 in the film with BaZrO3 inclusions, while the zerofield properties are not much affected. Combining surface resistance and surface reactance data we conclude (a) that BaZrO3 inclusions determine very deep and steep pinning wells and (b) that the pinning changes nature with respect to the pure film.Increasing pinning of vortex lines is an essential achievement for useful applications of superconductors in general, and of cuprate superconductors in particular due to the wide range of the H − T phase diagram where vortices are free or nearly free to move. Columnar defects are best suited to this aim, 1 but the introduction of such defects requires rather sophisticated techniques which are not suitable for mass production. Recently it was shown 2 that inclusions of BaZrO 3 (BZO) particles of dimensions in the 10-1000 nm range could determine a significant improvement of the dc properties of YBa 2 Cu 3 O 7−δ (YBCO) thin films. In particular, the critical current density 2,3 could be raised up to values useful for large scale dc applications, and the irreversibility line could be shifted above 10 T at 77 K. 4 A major interest comes from the easy incorporation of such sub-µm particles directly into the targets used for film deposition, thus making feasible the mass growth of very low losses superconductors. Pinning of vortices at high frequencies is desirable not only for devices operating in dc magnetic fields, but also because power handling is limited by depinning of selfnucleated vortices. In fact, tailored profiles of columnar defects have been shown to largely extend the linear regime at low microwave frequencies. 5 However, when the operating frequency increases, the dissipation due to oscillating vortices becomes increasingly difficult to reduce: with increasing frequency the amplitude of the vortex oscillation decreases, and becomes so small that only interactions between single vortices and pinning centers determine the response. In this regime the steepness of the pinning wells affects the balance between the reactive (elastic) and resistive (viscous) response, and the depth affects the creep of vortices. Even columnar defects, when the driving current oscillates in the high microwave range, determine at most a reduction of the dissipation of only ∼15%, as seen from measurements at * corresponding author. e-mail: silva@fis.uniroma3.it ∼50 GHz, 6 while in some cases the microwave dissipation raised after heavy-ion irradiation. 7 It seems reasonable to state that, up to now, no known artificial pinning centers have shown a significant reduction of the dissipation at very high frequencies. Measuring the response at the high edge of the microwave spectrum is a very stringent test for ...

Pulsed laser deposited thin Y Ba2Cu3O7−x (YBCO) films with pinning additions of 5 at. % Ba2Y TaO6 (BYTO) were compared to films with 2.5 at. % Ba2Y TaO6 + 2.5 at. % Ba2Y NbO6 (BYNTO) additions. Excellent magnetic flux-pinning at 77 K was obtained with remarkably high irreversibility fields greater than 10 T (YBCO-BYTO) and 11 T (YBCO-BYNTO), representing the highest ever achieved values in YBCO films.