Skyrmionic chains and lattices in s+id superconductors

Abstract

We report characteristic vortex configurations in s+id superconductors with time-reversal symmetry breaking, exposed to magnetic field. A vortex in the s+id state tends to have an opposite phase winding between s- and d−wave condensates. We find that this peculiar feature together with the competition between s- and d−wave symmetry results in three distinct classes of vortical configurations. When either s or d condensate absolutely dominates, vortices form a conventional lattice. However, when one condensate is relatively dominant, vortices organize in chains that exhibit skyrmionic character, separating the chiral components of the s±id order parameter into domains within and outside the chain. Such skyrmionic chains are found stable even at high magnetic field. When s and d condensates have comparable strength, vortices split cores in two chiral components to form full-fledged skyrmions, i.e., coreless topological structures with an integer topological charge, organized in a lattice. We provide characteristic magnetic field distributions of all states, enabling their identification in, e.g., scanning Hall probe and scanning SQUID experiments. These unique vortex states are relevant for high-Tc cuprate and iron-based superconductors, where the relative strength of competing pairing symmetries is expected to be tuned by temperature and/or doping level, and can help distinguish s+is and s+id superconducting phases.

Source-reported materials — not catalogue approval

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