Fractals Make Better Superconductors
European research team discovered that optimal superconductivity was obtained when the microstructure was most â€˜connectedâ€™
Researchers from Rome, Grenoble and London report that the strength of the superconductivity â€“ its ability to persist as temperature is increasedâ€“ correlates in certain oxide materials with structures visible over a range of length scales. Until now, scientists have focused on structure at the nanometer (0.0000001 millimeters) â€“ the distance between neighboring atoms - scale as the determinant of the unusually strong superconductivity of the oxides of copper. For the teamâ€™s published scientific article, the researchers describe how they used a new technique of X-ray microscopy to examine a copper oxide superconductor whose internal structure could be changed via simple heat treatments.
Ideal superconductivity occurred when the microstructure was most â€˜connected,â€™ meaning that it is possible to trace a path with the same nanostructure (exhibited by oxygen atoms) over a large distance. The microstructure in this case was â€˜fractalâ€™: if one were to zoom in on the materialâ€™s structure at increasing levels of magnification, its appearance would remain the same.