Ferran Vallès has been a very active member in the SUMAN group, both in research and in outreach activities. His research has dealt with the optimisation of superconducting thin films, prepared by chemical solution deposition, and with the incorporation of nanopartciles in the YBCO structure to enhance their properties.
How would you explain your research to a non-scientific audience?
The electrical current that flows through a superconductor without energy losses is limited to a certain value called “critical current”. In this research, I have investigated how the critical current is related to the nanosized defects of the atomic structure of the material. It has been performed by combination of electrical measurements and advanced microscopy, in collaboration with other doctoral students.
What are the main applications of your research? Could you give us an example?
High field magnets, magnetic resonance imaging, cables for electric power transmission, levitating trains... all this can be made out of superconductors with high critical currents.
Abstract:The fabrication of superconducting YBa2Cu3O7-x nanocomposite films by the incorporation of nanoparticles has demonstrated to strongly enhance the vortex pinning performances under applied magnetic fields and to reduce the effective anisotropy, ensuring great potential for their use in a broad number of applications. Different nanoparticle concentrations, sizes and growth process conditions lead to a rich variety of defects in the films, whose vortex pinning and vortex creep effectiveness depends on temperature and the magnitude and orientation of the magnetic field.It is shown that YBa2Cu3O7-x nanocomposites grown by chemical solution deposition provide simultaneously higher flux pinning and lower flux creep especially at low-intermediate temperatures and at low-intermediate magnetic fields. The region of this outstanding performance can be enlarged to larger fields and temperatures by further nanoengineering, where it has been shown that different defect landscapes can be particularly interesting for given operating conditions.