Researchers create and image a plasmonic topological quasiparticle spin texture in a structured silver film. The spin angular momentum components of linearly polarized light interacting with an Archimedean coupling structure with a designed geometric phase generate plasmonic waves with different orbital angular momenta.
These plasmonic fields undergo spin-orbit interaction, and their superposition generates an array of plasmonic vortices. Three of these vortices can form spin textures that carry non-trivial topological charge resembling magnetic meron quasiparticles. These spin textures are localized within a half-wavelength of light and exist on the timescale of the plasmonic field.
The researchers use ultrafast nonlinear coherent photoelectron microscopy to generate attosecond videos of the spatial evolution of the vortex fields; electromagnetic simulations and analytic theory confirm the presence of plasmonic topological quasiparticle. The quasiparticles form a chiral field, which breaks the time-reversal symmetry on a nanometer spatial scale and a 20-femtosecond timescale (the ‘nano-femto scale’). This transient creation of non-trivial spin angular momentum topology pertains to cosmological structure creation and topological phase transitions in quantum matter and may transduce quantum information on the nano-femto scale.