Vortex pinning properties at dc and microwave frequencies of YBa2Cu3O7-x films with nanorods and nanoparticles. (2nd June 2020)

• Record Type: Journal Article
• Authors: Bartolomé, E; Alcalà, J; Vallès, F; Puig, T; Obradors, X; Pompeo, N; Alimenti, A; Torokhtii, K; Rizzo, F; Augieri, A; Celentano, G; Silva, E; Palau, A
• Is Part Of: Superconductor science & technology. Volume 33:Number 7(2020:Jul.)
• Publication Date: 2020-06-02
• Subjects: YBCO superconductor -- critical current density -- flux pinning -- microwave measurements -- nanostructured films; Superconductivity -- Periodicals; Superconductors -- Periodicals; 537.623
• DOI: 10.1088/1361-6668/ab8f18
• Languages: English
• ISSNs: 0953-2048

Abstract

Abstract: YBa2 Cu3 O7−x (YBCO) nanocomposites for wire applications need to operate in a broad range of frequencies, ranging from dc in magnets to GHz in cavities and screenings of future particle accelerators. We have investigated the in-field and angular vortex pinning performance in dc and at 50 GHz of two types of nanocomposites, pulsed laser deposition (PLD) YBCO with mixed Ba2 YNbO6 + Ba2 YTaO6 (BYNTO) nanorods and chemical solution deposited (CSD) YBCO with BaHfO3 (BHO) nanoparticles (NPs), and the pristine counterpart films, grown on top of single-crystalline substrates. Transport measurements performed up to 9 T between 5 and 77 K show that CSD nanocomposites exhibit a smooth field decay and increased single-to-collective crossover field H * compared to pristine samples, associated to the enhanced isotropic pinning contribution induced by the NPs, while PLD films exhibit unchanged H * and superior critical current densities up to higher irreversibility fields, associated to the anisotropic contribution introduced by the rods. Microwave in-field measurements of the pinning constant kp revealed CSD NCs exhibit a qualitatively similar, but smoother kp ( H ) than pristine samples, whereas for PLD samples, a growing kp ( H ) dependence is observed as a result of the increased relevance of the stiffness of the fluxons pinned by nanorods.