BEGIN:VCALENDAR VERSION:2.0 PRODID:www.dresden-science-calendar.de METHOD:PUBLISH CALSCALE:GREGORIAN X-MICROSOFT-CALSCALE:GREGORIAN X-WR-TIMEZONE:Europe/Berlin BEGIN:VTIMEZONE TZID:Europe/Berlin X-LIC-LOCATION:Europe/Berlin BEGIN:DAYLIGHT TZNAME:CEST TZOFFSETFROM:+0100 TZOFFSETTO:+0200 DTSTART:19810329T030000 RRULE:FREQ=YEARLY;INTERVAL=1;BYMONTH=3;BYDAY=-1SU END:DAYLIGHT BEGIN:STANDARD TZNAME:CET TZOFFSETFROM:+0200 TZOFFSETTO:+0100 DTSTART:19961027T030000 RRULE:FREQ=YEARLY;INTERVAL=1;BYMONTH=10;BYDAY=-1SU END:STANDARD END:VTIMEZONE BEGIN:VEVENT UID:DSC-23261 DTSTART;TZID=Europe/Berlin:20261027T100000 SEQUENCE:1793083201 TRANSP:OPAQUE DTEND;TZID=Europe/Berlin:20261027T110000 URL:https://www.dresden-science-calendar.de/calendar/en/detail/23261 LOCATION:IFW\, Helmholtzstraße 2001069 Dresden SUMMARY:Grinenko: Flux quantum fractionalization and unquantized vortices i n superconductors CLASS:PUBLIC DESCRIPTION:Speaker: Dr. Vadim Grinenko\nInstitute of Speaker: Shanghai Jia o Tong University\nTopics:\n\n Location:\n Name: IFW (B3 E.26\, IFW Dresd en)\n Street: Helmholtzstraße 20\n City: 01069 Dresden\n Phone: \n Fa x: \nDescription: Magnetic flux quantization is a defining hallmark of sup erconductivity\, traditionally constraining vortices to carry integer mult iples of the flux quantum Φ₀. Recent advances in multiband superconduct ors challenge this paradigm by demonstrating the emergence of vortices car rying fractional\, continuously tunable flux [1-3]. Here\, we overview rec ent experimental breakthroughs to present a unified picture of vortex deco nfinement\, and emergent composite excitations in multicomponent supercond ucting systems. Three years ago\, scanning SQUID magnetometry in Ba₁₋ ₓKₓFe₂As₂ revealed mobile vortices carrying a nonuniversal\, tempe rature-dependent fraction of Φ₀\, demonstrating that flux quantisation can be continuously violated in multiband systems [1]. Complementary spect roscopic imaging via scanning tunnelling microscopy further shows that int eger vortices can split into multiple fractional core singularities\, esta blishing a direct link between multiband phase structure and vortex-core f ractionalization [2]. These findings are consistent with theoretical predi ctions that multicomponent superconducting condensate can support phase wi ndings in the individual components of the order parameter [4\,5]. Extend ing these observations\, recent scanning SQUID magnetometry visualized the real-space deconfinement of integer flux vortices: integer vortices can s pontaneously split into spatially separated\, yet correlated\, fractional- flux objects stabilized by pinning and thermal fluctuations [3]. Notably\, the flux of these constituents exhibits an anticorrelated temperature dep endence while conserving the total flux\, forming a “see-saw” redistri bution mechanism. This behavior reveals a striking analogy to quark confin ement and deconfinement\, where fractional vortices act as linearly intera cting constituents of composite topological objects. Together\, these stud ies establish fractional flux unquantized vortices as robust\, mobile\, an d tunable excitations in multiband superconductors. Their existence expand s the fundamental understanding of topological defects beyond conventional quantization arguments and opens new avenues for engineering novel fluxon ics devices. Moreover\, the stability of unquantized vortices establishes them as candidates for observing anyons\, which may be represented\, as sh own by Frank Wilczek [6]\, as an integer charge bound to a fractional flux tube. These results position multicomponent superconductors as a promisin g platform for exploring emergent topology and fractionalized quantum matt er. Bibliography 1. Y. Iguchi\, et al. Science\, 380(6651)\, 1244–1247 (2023). 2. Y. Zheng\, et al. Science 393\, 80-84 (2026). 3. Q. Z. Zhou et al. arXiv:2408.05902 (2024). 4. E. Babaev\, Model. Phys. Rev. Lett. 89\, 0 67001(2002). 5. I. Timoshuk and E. Babaev\, New J. Phys. 27 (2025) 123501. 6. F. Wilczek\, Phys. Rev. Lett. 48\, 1144–1146 (1982). DTSTAMP:20261027T204443Z CREATED:20261027T064001Z LAST-MODIFIED:20261027T064001Z END:VEVENT END:VCALENDAR