Observation of quantum vortex core fractionalization and skyrmion formation in a superconductor
Summary
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. Here, we report signatures of quantum vortex core fractionalization on the potassium-terminated surface of a multiband superconductor KFe2As2. The observed splitting of single integer-flux vortices into several fractiona
Content
# Observation of quantum vortex core fractionalization and skyrmion formation in a superconductor
*Published: 2026 May 21*
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. Here, we report signatures of quantum
vortex core fractionalization on the potassium-terminated surface of a multiband
superconductor KFe2As2. 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 ℂP2 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.
DOI: 10.1126/science.ads0189