Magnetoplasmonic nanoantennas: theory and applications
CIC nanoGUNE Seminars
- Speaker
-
Nicolo Maccaferri, Nanomagnetism Group
- When
-
2015/06/29
13:00 - Place
- nanoGUNE seminar room, Tolosa Hiribidea 76, Donostia - San Sebastian
- Add to calendar
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The rapidly developing field of magnetoplasmonics merges the concepts from
plasmonics and magnetism to realize novel and unexpected phenomena for the
manipulation of light at the nanoscale.
Ferromagnetic nanoantennas support localized surface plasmons and exhibit
sizeable magneto-optical activity under external magnetic fields [1-3]. Here
we explore the influence of the phase of localized surface plasmon resonances
on the magneto-optical activity of ferromagnetic nanoantennas. We demonstrate
that these systems can be described as two orthogonal damped oscillators
coupled by the spin-orbit interaction. We prove that only the spin-orbit
induced transverse plasmon plays and active role on the magneto-optical
properties by controlling the relative amplitude and phase lag between the two
oscillators [3]. The theoretical predictions are fully confirmed by magneto-
optical Kerr effect and optical extinction measurements in nanostructures of
different size and shape.
We also present an overview of potential technological applications of
magnetoplasmonic nanoantennas, opening new perspectives towards a variety of
emerging technologies such as ultrasensitive molecular sensing [4], non-
reciprocal metasurfaces for the control of the light polarization states at
the nanoscale [5], and out-performing plasmon rulers [6].
Based on our previous theoretical findings, we first show novel ways to
exploit such nanoantennas for the active manipulation of the light
polarization states. We introduce design rules for highly tunable active
magnetoplasmonic elements in which we can tailor at will the amplitude and
sign of the Kerr response over a broad spectral range [4].
Then we demonstrate how magnetoplasmonic nanoantennas can be exploited as
ultrasensitive sensors for biotechnological applications [5]. Systems allowing
label-free molecular detection are expected to have enormous impact on
biochemistry and biomedicine, and are therefore subject to intense
investigation. We propose an innovative and alternative route based on
magnetoplasmonic nanoantennas, which enables radically improved sensitivity,
clearly outperforming recently reported plasmon based sensors. Most
remarkably, we achieved a local surface sensitivity of two orders of magnitude
higher than the best values reported for nanoplasmonic sensors. Such
sensitivity corresponds to a mass of ~0.8 atto g/nanoantenna of polyamide-6.6
(n=1.51), which is representative for a large variety of polymers, peptides
and proteins.
Finally, we focused on the emerging concept of plasmon rulers, in which strong
near-field coupling of plasmon antenna elements is employed to obtain
structural information on the nanoscale. We demonstrate how magnetoplasmonic
rulers based on ferromagnetic dimers allow for the measurements of small and
large nanoscale distances alike with two orders of magnitude higher precision
than current state-of-the-art plasmon rulers [6].
References
[1] J. Chen et al. Small 7, 2341 (2011).
[2] V. Bonanni et al. Nano Lett. 11, 5333 (2011).
[3] N. Maccaferri et al. Phys. Rev. Lett. 111, 167401 (2013).
[4] K. Lodewijks et al., Nano Lett. 14, 7207 (2014).
[5] N. Maccaferri et al., Nat. Commun. 6, 6150 (2015).
[6] I. Zubritzskaya et al., Nano Lett., 15, 3204 (2015).