Observation of superconducting vortices carrying a temperature-dependent fraction of the flux quantum

Abstract

The magnetic response is a state-defining property of superconductors. The magnetic flux penetrates type-II bulk superconductors by forming quantum vortices when the enclosed magnetic flux is equal to the magnetic flux quantum. The flux quantum is the universal quantity that depends only on the ratio of fundamental constants: the electron charge and the Planck constant. This work investigates the vortex state in the hole-overdoped Ba${}_{1-x}$K${}_x$Fe${}_2$As${}_2$ by using scanning superconducting quantum interference device (SQUID) magnetometry. We observed quantum vortices that carry only a fraction of the flux quantum, which vary continuously with temperature. This finding establishes the phenomenon that superconductors support quantum vortices with non-universally quantized magnetic flux. Furthermore, the demonstrations of the mobility of the fractional vortices and the manipulability of their positions open up a route for future fluxonics applications.

arXiv comment19 pages, 9 figures

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Cited by in corpus (22)

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• Coreless vortices as direct signature of chiral $d$-wave superconductivity
• Robust and tunable coreless vortices and fractional vortices in chiral $d$-wave superconductors
• Probing Vortex Dynamics in 2D Superconductors with Scanning Quantum Microscope
• Atomic-scale Frustrated Josephson Coupling and Multi-condensate Visualization in FeSe
• Neutron Spin Resonance Near a Lifshitz Transition in Overdoped Ba${}_{0.4}$K${}_{0.6}$Fe${}_2$As${}_2$
• Tuning Bound States of Symmetry-Breaking Vortices via Unidirectional Charge Density Wave in a Transition-Metal Dichalcogenide Superconductor
• Advanced SQUID-on-lever scanning probe for high-sensitivity magnetic microscopy with sub-100-nm spatial resolution
• Delocalization of vortex magnetic field near a planar defect
• Ultrasound evidence for multicomponent superconducting order parameter in Ba${}_{1-x}$K${}_x$Fe${}_2$As${}_2$ with electron quadrupling phase
• Microscopic solutions for vortex clustering in two-band type-1.5 superconductors
• Observation of vortex stripes in UTe${}_2$
• Fractional vortex array realized at twin boundary in a nematic superconductor
• Borromean supercounterfluids at finite temperatures
• Microscopic properties of fractional vortices and domain walls in three-band $s+is$ superconductors
• DC-driven separation of fractional flux quanta in two-band superconductors
• Fractional vorticity, Bogomol'nyi-Prasad-Sommerfield systems and complex structures for the (generalized) spinor Gross-Pitaevskii equations
• Unconventional magnetization in the multiphase superconductor PdBi${}_2$
• Unconventional superconducting correlations in fermionic many-body scars
• Magnetic Imaging with High Spatial Resolution Using a Single Niobium-Nitride-Based Three-Dimensional Nanobridge Junction