New technologies to tackle the risks of our power-hungry society: getting closer to room temperature superconductivity

Superconductivity, discovered one century ago, is one of most exciting phenomena in Condensed Matter Physics by its intrinsic scientific interest and by its potential importance for electronic applications. Superconductors have zero resistance and cables made out of these materials can carry electrical currents with zero losses. This makes it possible to build the most powerful magnets, which are used in magnetic resonance imaging and to guide particles in accelerators such as LHC, to fabricate electric generators and motors that reduce emissions, to make fault current limiters to avoid blackouts, and a long etcetera of applications which are under continuous development. Superconductivity appears at low temperatures, which implies that all applications of superconductors require cooling. Particularly interesting for applications are those showing superconductivity above some tens of Kelvin, the socalled high critical temperature (HTc) superconductors, where cooling requirements are much more affordable. However, the current carrying capability of these materials is limited by the motion of quanta of magnetic flux, called vortices, which form inside the superconductors under the action of a current. To stop vortex dissipation is, hence, a primary requirement to achieve any practical application of superconductors. Within this project, advanced nanofabrication tools will be used to improve vortex pinning through nanopatterning in HTc superconductors. This novel approach will allows us to best optimize their ability to carry electrical current with zero resistance. To achieve this objective, I will combine macroscopic transport and local measurements of the critical current as a function of the temperature and magnetic field. For the local measurements, I will use extremely sensitive microscopes (Scanning Tunneling Microscopy), available at the Low Temperature Laboratory of the Universidad Autónoma de Madrid. I will visualize a large number of vortices in a single image and track them one by one as a function of the temperature, magnetic field and current. I will correlate these results with current carrying experiments and provide engineers with new means to improve applications based on HTc superconductors and better utilize their potential.