Chiral CP^2 skyrmions in three-band superconductors

Abstract

It is shown that under certain conditions, three-component superconductors (and in particular three-band systems) allow stable topological defects different from vortices. We demonstrate the existence of these excitations, characterized by a $C{P}^2$ topological invariant, in models for three-component superconductors with broken time reversal symmetry. We term these topological defects "chiral $G{L}^{(3)}$ skyrmions", where "chiral" refers to the fact that due to broken time reversal symmetry, these defects come in inequivalent left- and right-handed versions. In certain cases these objects are energetically cheaper than vortices and should be induced by an applied magnetic field. In other situations these skyrmions are metastable states, which can be produced by a quench. Observation of these defects can signal broken time reversal symmetry in three-band superconductors or in Josephson-coupled bilayers of $s_{\pm }$ and s-wave superconductors.

minor presentation changes; replaced journal version; 30 pages, 21 figures

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• Skyrmionic chains and lattices in $s+id$ superconductors
• Vortex chains due to nonpairwise interactions and field-induced phase transitions between states with different broken symmetry in superconductors with competing order parameters
• Fluctuation effects in rotating Bose-Einstein condensates with broken $\mathrm{SU}(2)$ and $\mathrm{U}(1)\times \mathrm{U}(1)$ symmetries in the presence of intercomponent density-density interactions
• Spontaneous symmetry breaking in dual-core baby-Skyrmion systems