Nanostructured supercondutors

Superconducting cuprate nanowires are studied to establish the relation between synthesis and processing parameters with their properties. These nanofibers are produced by the Solution Blow Spinning (SBS) technique in GSMA/Unesp, and their superconducting properties are investigated in GSM/UFSCar. The primary motivation for fabricating these superconductors is to improve their performance for different applications such as single photon detectors.

Current project: 

Superconductivity at different textures: sintered granulars, thin films of variable thickness and granular structures formed by simple geometric elements juxtaposed

member

This research proposal comprises three subprojects. One of them involves the production of superconducting films with different thicknesses, in addition to wedge-shaped samples (variable thickness) aiming to study thickness-dependent changes in the morphology of the penetrated flow. Furthermore, the variation of critical current density with thickness will also be investigated, through its effects on the triggering and evolution of flux avalanches. In the second subproject, devices formed by the juxtaposition of simple geometric elements will be studied, with different thicknesses and varying values of the ratio between the critical current of the junction (intergranular) and that of the individual parts (intragranular). The other subproject is aimed at studying variations in the synthesis and processing of YBa2Cu3O7-x (YBCO) in the search for favorable conditions to increasing the critical current of nanofibers - eventually transformed into powder - produced by the innovative technique called Solution Blow Spinning. Three different conditions will be studied: (i) introduction of non-superconducting Y2BaCuO5 particles; (ii) addition of nickel (magnetic) and zinc (non-magnetic) - in the YBCO matrix; (iii) variation of nanofiber synthesis using different molar masses of the PVP polymer.

Past project: 

Macro and mesoscopic superconductivity: synthesis of ceramic materials and computational simulations based on the TDGL theory

member

The studies proposed in this manuscript follow two research lines in the superconductivity area with materials at macro and nanoscopic scales. One is focused on the experimental area, which is based on the production and characterization of non-conventional superconductors, e.g., the oxide materials. We are proposing the study of BSCCO (B2212) and YBCO materials—the last one with stoichiometry Y123 and Y358. The samples will be produced by the Solution Blow Spinning technique, and synthesizing the precursor solutions will follow the Sol-Gel process. The samples will be characterized by TGA/DTA, XRD, EDX, SEM, magnetometry, and electrical transport. The analysis of the superconducting properties, including the studies of the weak links' superconductivity, will be carried out by electric and magnetic measurements. The other research area is focused on the theoretical study of superconducting materials with mesoscopic dimensions. The motivation for such a study lies in the advances in nanofabrication techniques, which intensified experimental studies of superconducting materials at the nanoscale. An application of such materials is the single photon detectors. In those devices, a current with intensity near its critical value flows in the material. When a photon reaches the superconductor, it generates a local hot spot, which destroys the superconductivity. Then, a resistive state is created, and a peak in the measured potential occurs, counting one photon. On the other hand, with the transport of high-intensity currents, a resistive state can appear due to the nucleation of kinematic vortices due to the creation of phase slip lines (not by magnetic fields as in the case of Abrikosov vortices). In this way, one of the areas that barely appears in the literature is related to the mechanisms of energy dissipation and heat diffusion in mesoscopic superconductors. Thus, the theoretical studies will be carried out by simulating those systems using the time-dependent Ginzburg-Landau theory, which will be appropriately adapted to consider energy dissipation and heat diffusion.

Recent publications: