Séminaire de Physique ThéoriqueKnotted superconducting vortices – Hopf-Skyrme Topological Excitations as superconducting Kelvin knots
Julien Garaud (IDP, Tours)
Thursday 21 March 2019 14:00 - Tours - Salle 1180 (Bât E2)
In the late 19th century, Kelvin conjectured that atoms consisted of linked and knotted vortex loops in luminiferous aether. This "vortex-atom" theory became obsolete after Michelson and Morley's experiment ruled out the existence of aether. It had a long-lasting impact and still resonates with modern physics concepts. The fact that many of the key macroscopic properties of superconductors and superfluids are understood to be controlled by the underlying behavior of vortices and vortex loops can be seen as a reminiscent idea of the "vortex-atom" theory. Unlike in Kelvin's theory where loops are perpetual, superconducting and superfluid vortex loops feature an intrinsic instability to shrink. Here I report that certain multicomponent superconducting states do support stable knotted vortices. The stability occurs when superconductors feature a relatively strong Andreev-Bashkin dissipationless drag. That situation is likely to happen in the vicinity of the transitions to certain phases such as paired phase due to strong correlations or Fulde-Ferrell-Larkin-Ovchinnikov state. The stable knots I report are bound state of linked and knotted loops of vortices carrying a fraction of the flux quantum. These objects are characterized by the nontrivial topological properties associated with the maps between three-spheres.