Skyrmion bags of light in plasmonic moiré superlattices

Abstract

The study of van der Waals heterostructures with an interlayer twist, known as twistronics, has been instrumental in advancing the understanding of many strongly correlated phases, many of which derive from the topology of the physical system. Here we explore the application of the twistronics paradigm in plasmonic systems with a non-trivial topology by creating a moiré skyrmion superlattice using two superimposed plasmonic skyrmion lattices with a relative twist. We measure the complex electric field distribution of the moiré skyrmion superlattice using time-resolved polarimetric photoemission electron microscopy. Our results show that each supercell has very large topological invariants and harbours a skyrmion bag, the size of which is controllable by the twist angle and centre of rotation. Our work indicates how twistronics can enable the creation of various topological features in optical fields and provides a route for locally manipulating electromagnetic field distributions. Skyrmion bags—textures comprising multiple skyrmions contained within a larger skyrmion—have been reported in several condensed matter systems. Now an optical analogue of these structures has been observed in plasmonic moiré superlattices.