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Register a new userMultimodal Plasmonics in Fused Colloidal Networks
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Authors
Alexandre Teulle
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Harnessing the optical properties of noble metals down to the nanometer-scale is a key step towards fast and low-dissipative information processing. At the 10-nm length scale, metal crystallinity and patterning as well as probing of surface plasmon (SP) properties must be controlled with a challenging high level of precision. Here, we demonstrate that ultimate lateral confinement and delocalization of SP modes are simultaneously achieved in extended self-assembled networks comprising linear chains of partially fused gold nanoparticles. The spectral and spatial distributions of the SP modes associated with the colloidal superstructures are evidenced by performing monochromated electron energy loss spectroscopy with a nanometer-sized electron probe. We prepare the metallic bead strings by electron beam-induced interparticle fusion of nanoparticle networks. The fused superstructures retain the native morphology and crystallinity but develop very low energy SP modes that are capable of supporting long range and spectrally tunable propagation in nanoscale waveguides.
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Two-dimensional materials exhibit a fascinating range of electronic and photonic properties vital for nanophotonics, quantum optics and emerging quantum information technologies. Merging concepts from the fields of ab initio materials science and nanophotonics, there is now an opportunity to engineer new photonic materials whose optical, transport, and scattering properties are tailored to attain thermodynamic and quantum limits. Here, we present first-principles calculations predicting that Argentene, a single-crystalline hexagonal close-packed monolayer of Ag, can dramatically surpass the optical properties and electrical conductivity of conventional plasmonic materials. In the low-frequency limit, we show that the scattering rate and resistivity reduce by a factor of three compared to the bulk three-dimensional metal. Most importantly, the low scattering rate extends to optical frequencies in sharp contrast to e.g. graphene, whose scattering rate increase drastically in the near-infrared range due to optical-phonon scattering. Combined with an intrinsically high carrier density, this facilitates highly-confined surface plasmons extending to visible frequencies. We evaluate Argentene across three distinct figures of merit, spanning the spectrum of typical plasmonic applications; in each, Argentene outperforms the state-of-the-art. This unique combination of properties will make Argentene a valuable addition to the two-dimensional heterostructure toolkit for quantum electronic and photonic technologies.
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