When the size of a superconductor becomes comparable with these characteristic lengths, the properties of the superconductor can change dramatically, including the critical temperature, critical magnetic field, and vortex structures. A collaborative study led by the group of Dr. Joe Stroscio at CNST NIST Gaithersburg has performed scanning tunneling microscopy (STM) measurements on superconducting nanostructured disks of polycrystalline YPtBi, created by local current annealing inside the STM tunneling junction. The spectra show non–BCS behavior, possibly suggesting nonconventional pairing,with different energy gaps, critical temperature, and critical magnetic fields found in the center region versus the perimeter region of the nanostructure. By varying magnetic field, the sequential addition of single vortices to the nanostructure was shown, cumulating into a giant vortex ring at 1.25 T. These measurements demonstrate an interesting method of creating tailored nanostructured superconductors with complex superconducting materials for a variety of future applications.

See published article in Physical Review