Complete report - Donostia International Physics Center - Euskal ...

2011 DIPC Highlight
Plasmonic nickel antennas
J. Chen, P. Albella, Z. Pirzadeh, P. Alonso-Gonzalez, F. Huth, S. Bonetti, V. Bonanni, J. Akerman, J. Nogues,
P. Vavassori, A. Dmitriev, J. Aizpurua, and R. Hillenbrand
Small 7, 2341-2347 (2011)
Shift between the spectral response
of the Near-field and the Far-field
identified as due to the large damping.
Plasmonic antennas are commonly implemented with use of gold or silver as materials, but many
other materials can also perform as good field enhancers in spite of the large energy losses associated
with them. In this work the fundamental optical properties of pure nickel nanoantennas
are studied as a step towards understanding and engineering magnetically controllable optical
nanoantennas. This novel material can be extremely useful for many developing technologies
including biosensors, lasers, and solar cells.
The authors have studied the fundamental optical properties of pure nickel nanostructures by far-field
extinction spectroscopy and optical near-field microscopy, providing direct experimental evidence of the
existence of particle plasmon resonances predicted by theory. The synthesis of the Ni nanoantennas and
the far-field optical characterization has been developed in Göteborg, Sweden, at Chalmers University of
Technology, whereas the near-field characterization has been done with use of a scattering-type nearfield
optical microscope (s-SNOM) at the center for NanoScience and Nanotechnology nanoGUNE in San
Sebastián. Researchers at DIPC have described theoretically the near-field and far-field response of the Ni
antennas by means of full electrodynamical calculations. A comparison of the experimental and calculated
near-field maps allow for unambiguous identification of dipolar plasmon modes in the Ni nanoparticles.
Near-field images of the dipolar plasmonic modes are shown in the figure.
Furthermore, by comparing the calculated near-field and the far-field spectra, dramatic shifts between
the near-field and far-field plasmon resonance are found. These shifts are more pronounced than in typical
gold nanoantennas. Based on a simple damped harmonic oscillator
model to describe plasmonic resonances, it is possible to explain
these shifts as due to plasmon damping. Ni nanoantennas are thus
identified as good platforms to reveal the spectral shifts due to their
relatively large damping.
Ni nanoparticles can perform as
plasmonic nanoantennas.
Near-field amplitude of Ni nanodisks acting as plasmonic antennas. The diameter of the disks is 90 nm. The
dipolar mode is excited in several disks resonantly at a wavelength of 633 nm.
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