Speaker
Description
One of the fundamental properties of a superconductor is expulsion of magnetic field. The only known exception was when they form a special type of topological defect: quantum vortices, which consist of a core singularity with circulating currents. The London’s quantization condition implies that there is one core singularity per quantum of magnetic flux in single-component superconductors. Here, we report the first scanning tunneling microscopy observation of quantum vortex core fractionalization on the potassium-terminated surface of the multiband superconductor KFe2As2. The observed splitting of an integer-flux vortex into several fractional vortices results in a disparity between the number of flux quanta and the number of vortex cores. These fractional vortices tend to arrange in chains, and microscopic calculations show that such chains are characterized by a CP2 skyrmionic topological invariant hence constituting a different type of topological defects: superconducting skyrmions. We discovered significant spectroscopy difference between integer and fractional vortices comprising skyrmions.
| Session Selection | Condensed Matter |
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