| 1. |
- Kataja, Mikko, et al.
(author)
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Hybrid plasmonic lattices with tunable magneto-optical activity
- 2016
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In: Optics Express. - : Optica Publishing Group. - 1094-4087. ; 24:4, s. 3652-3652
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Journal article (peer-reviewed)abstract
- We report on the optical and magneto-optical response of hybrid plasmonic lattices that consist of pure nickel and gold nanoparticles in a checkerboard arrangement. Diffractive far-field coupling between the individual emitters of the lattices results in the excitation of two orthogonal surface lattice resonance modes. Local analyses of the radiation fields indicate that both the nickel and gold nanoparticles contribute to these collective resonances and, thereby, to the magneto-optical activity of the hybrid arrays. The strong effect of noble metal nanoparticles on the magneto-optical response of hybrid lattices opens up new avenues for the realization of sensitive and tunable magneto-plasmonic nanostructures.
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| 2. |
- Maccaferri, Nicolò, Dr. 1988-, et al.
(author)
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Anisotropic Nanoantenna-Based Magnetoplasmonic Crystals for Highly Enhanced and Tunable Magneto-Optical Activity
- 2016
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In: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 16:4, s. 2533-2542
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Journal article (peer-reviewed)abstract
- We present a novel concept of a magnetically tunable plasmonic crystal based on the excitation of Fano lattice surface modes in periodic arrays of magnetic and optically anisotropic nanoantennas. We show how coherent diffractive far-field coupling between elliptical nickel nanoantennas is governed by the two in-plane, orthogonal and spectrally detuned plasmonic responses of the individual building block, one directly induced by the incident radiation and the other induced by the application of an external magnetic field. The consequent excitation of magnetic field-induced Fano lattice surface modes leads to highly tunable and amplified magneto-optical effects as compared to a continuous film or metasurfaces made of disordered noninteracting magnetoplasmonic anisotropic nanoantennas. The concepts presented here can be exploited to design novel magnetoplasmonic sensors based on coupled localized plasmonic resonances, and nanoscale metamaterials for precise control and magnetically driven tunability of light polarization states.
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| 3. |
- Maccaferri, Nicolò, et al.
(author)
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Effects of a non-absorbing substrate on the magneto-optical Kerr response of plasmonic ferromagnetic nanodisks
- 2014
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In: Physica Status Solidi (a) applications and materials science. - : Wiley. - 1862-6300 .- 1862-6319. ; 211:5, s. 1067-1075
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Journal article (peer-reviewed)abstract
- Magnetoplasmonics is an emerging field of intense research on materials combining magnetic and plasmonic functionalities. The novel optical and magneto-optical (MO) properties displayed by these materials could allow the design of a new class of magnetically controllable optical nano-devices. In this work, we investigate the effects of a non-absorbing (insulating) substrate on the MO activity of pure ferromagnetic disk-shaped nanostructures supporting localized plasmon resonances. We show that the red-shift of the localized plasmon resonance, related to the modification of the localization of the electromagnetic field due to the substrate, is not the only effect that the substrate has on the MO response. We demonstrate that the reflectivity of the substrate itself plays a key role in determining the MO response of the system. We discuss why it is so and provide a description of the modeling tools suitable to take into account both effects. Understanding the role of the substrate will permit a more aware design of magnetoplasmonic nanostructured devices for future biotechnological and optoelectronic applications. [GRAPHICS] Ferromagnetic nickel nanodisk in vacuum (left) and on a non-absorbing substrate (right), illuminated by linearly polarized light. The polarization of the reflected field is changed in the first case due to a combination of intrinsic magneto-optical properties and the nanoconfinement of the material. In the second case, the polarization of the reflected light is affected also by the presence of the substrate.
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| 4. |
- Maccaferri, Nicolò, et al.
(author)
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Polarizability and magnetoplasmonic properties of magnetic general nanoellipsoids
- 2013
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In: Optics Express. - : Optica Publishing Group. - 1094-4087. ; 21:8, s. 9875-9889
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Journal article (peer-reviewed)abstract
- An approach to compute the polarizability tensor of magnetic nanoparticles having general ellipsoidal shape is presented. We find a surprisingly excellent quantitative agreement between calculated and experimental magneto-optical spectra measured in the polar Kerr configuration from nickel nanodisks of large size (exceeding 100 nm) with circular and elliptical shape. In spite of its approximations and simplicity, the formalism presented here captures the essential physics of the interplay between magneto-optical activity and the plasmonic resonance of the individual particle. The results highlight the key role of the dynamic depolarization effects to account for the magneto-optical properties of plasmonic nanostructures.
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| 5. |
- Maccaferri, Nicolò, et al.
(author)
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Tuning the Magneto-Optical Response of Nanosize Ferromagnetic Ni Disks Using the Phase of Localized Plasmons
- 2013
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In: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 111:16
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Journal article (peer-reviewed)abstract
- We explore the influence of the phase of localized plasmon resonances on the magneto-optical activity of nanoferromagnets. 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 an active role on the magneto-optical properties by controlling the relative amplitude and phase lag between the two oscillators. Our theoretical predictions are fully confirmed by magneto-optical Kerr effect and optical extinction measurements in nanostructures of different size and shape.
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| 6. |
- Pourjamal, Sara, et al.
(author)
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Hybrid Ni/SiO2/Au dimer arrays for high-resolution refractive index sensing
- 2018
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In: Nanophotonics. - : Walter de Gruyter. - 2192-8614. ; 7:5, s. 905-912
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Journal article (peer-reviewed)abstract
- We introduce a novel magnetoplasmonic sensor concept for sensitive detection of refractive index changes. The sensor consists of a periodic array of Ni/SiO2/Au dimer nanodisks. Combined effects of near-field interactions between the Ni and Au disks within the individual dimers and far-field diffractive coupling between the dimers of the array produce narrow linewidth features in the magneto-optical Faraday spectrum. We associate these features with the excitation of surface lattice resonances and show that they exhibit a spectral shift when the refractive index of the surrounding environment is varied. Because the resonances are sharp, refractive index changes are accurately detected by tracking the wavelength where the Faraday signal crosses 0. Compared to random distributions of pure Ni nanodisks or Ni/SiO2/Au dimers or periodic arrays of Ni nanodisks, the sensing figure of merit of the hybrid magnetoplasmonic array is more than one order of magnitude larger
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| 7. |
- Pourjamal, Sara, et al.
(author)
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Tunable magnetoplasmonics in lattices of Ni/SiO2/Au dimers
- 2019
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In: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 9:1
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Journal article (peer-reviewed)abstract
- We present a systematic study on the optical and magneto-optical properties of Ni/SiO2/Au dimer lattices. By considering the excitation of orthogonal dipoles in the Ni and Au nanodisks, we analytically demonstrate that the magnetoplasmonic response of dimer lattices is governed by a complex interplay of near- and far-field interactions. Near-field coupling between dipoles in Ni and low-loss Au enhances the polarizabilty of single dimers compared to that of isolated Ni nanodisks. Far-field diffractive coupling in periodic lattices of these two particle types enlarges the difference in effective polarizability further. This effect is explained by an inverse relationship between the damping of collective surface lattice resonances and the imaginary polarizability of individual scatterers. Optical reflectance measurements, magneto-optical Kerr effect spectra, and finite-difference time-domain simulations confirm the analytical results. Hybrid dimer arrays supporting intense plasmon excitations are a promising candidate for active magnetoplasmonic devices.
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