Observation of quantum vortex core fractionalization and skyrmion formation in a superconductor.
basic_science · Level V
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- Record sourced from PubMed, PMID 42166558.
- Also identified by DOI 10.1126/science.ads0189.
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Abstract
Magnetic fields can penetrate a superconductor in the form of quantum vortices, which consist of a core singularity with circulating currents. London's quantization implies that there is one core singularity per quantum of magnetic flux in single-component superconductors. In this study, we report signatures of quantum vortex core fractionalization on the potassium-terminated surface of a multiband superconductor, KFe<sub>2</sub>As<sub>2</sub>. The observed splitting of single integer-flux vortices into several fractional vortices results in a disparity between the numbers of flux quanta and vortex cores. These fractional vortices often arrange in chains, which calculations show are characterized by a ℂP<sup>2</sup> skyrmionic topological invariant; this constitutes a different type of topological defect: the chiral skyrmion. The disparate natures of integer and fractional vortices comprising skyrmions lead to distinct spectroscopic signatures.