Observation of Topologically Robust Localized Magnetic Plasmon Skyrmions

Abstract: Optical skyrmions have recently been constructed by tailoring electric or spin field distributions through the interference of multiple surface plasmon polaritons, offering promising features for advanced information processing, transport and storage. Here, we construct topologically robust plasmonic skyrmions in a wisely tailored space-coiling meta-structure supporting magnetic localized spoof plasmons (LSPs), which are strongly squeezed down to {\lambda}3/106 and do not require stringent external interference conditions. By directly measuring the spatial profile of all three vectorial magnetic fields, we reveal multiple {\pi}-twist target skyrmion configurations mapped to multi-resonant near-equidistant LSP eigen-modes. The real-space topological robustness of these skyrmion configurations is confirmed by arbitrary deformations of the meta-structure, demonstrating flexible skyrmionic textures with arbitrary shapes. The observed magnetic LSP skyrmions pave the way to ultra-compact and topologically robust plasmonic devices, such as flexible sensors, wearable electronics and ultra-compact antennas.