Jérôme Martin, Julien Proust, Davy Gérard, Jérôme Plain, Mathieu Kociak,
Multipolar plasmonic resonances in aluminum nanostructures revealed by Electron Energy Loss Spectroscopy
13th international conference of Near-field Optics and Nanophotonics (NFO)
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Aluminum is a very appealing material for future nanoplasmonics. It is cheap, widely available, compatible with optoelectronic devices and exhibits plasmonic properties over a wide range of energies, up to the deep UV. In this communication, we report on the high resolution imaging of multipolar plasmonic resonances in aluminum nanoantennas using Electron Energy Loss Spectroscopy (EELS). Plasmonic resonances ranging from near infrared to ultraviolet are measured. The spatial distributions of the multipolar resonant modes are mapped according to the nanoantennas geometries and their energy dispersion is retrieved. The losses in the aluminum antennas are studied through the full width at half maximum of the resonances, unveiling the weight of both interband and radiative damping mechanisms of the different multipolar resonances. In the blue-UV spectral range, high order resonant modes present a quality factor up to 8, two times higher than low order resonant modes at the same energy. This study demonstrates that near infrared to ultraviolet tunable multipolar plasmonic resonances in aluminum nanoantennas with relatively high quality factors can be engineered. Aluminum nanoantennas are thus an appealing alternative to gold or silver ones in the near infrared to visible part of the spectrum, and can be efficiently used for UV plasmonics.