References of "Vavassori, Paolo"
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See detailElectrophoretic deposition of WS2 flakes on nanoholes arrays – role of the used suspension medium
Mosconi, Dario; Giovannini, Giorgia; Maccaferri, Nicolò UL et al

in Materials (in press)

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See detailTunable magnetoplasmonics in lattices of Ni/SiO2/Au dimers
Pourjamal, Sara; Kataja, Mikko; Maccaferri, Nicolò UL et al

in Scientific Reports (2019), 9

We present a systematic study on the optical and magneto-optical properties of Ni/SiO2/Au dimer lattices. By consideringthe excitation of orthogonal dipoles in the Ni and Au nanodisks, we analytically ... [more ▼]

We present a systematic study on the optical and magneto-optical properties of Ni/SiO2/Au dimer lattices. By consideringthe excitation of orthogonal dipoles in the Ni and Au nanodisks, we analytically demonstrate that the magnetoplasmonicresponse of dimer lattices is governed by a complex interplay of near- and far-field interactions. Near-field coupling betweendipoles in Ni and low-loss Au enhances the polarizabilty of single dimers compared to that of isolated Ni nanodisks. Far-fielddiffractive 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 theimaginary polarizability of individual scatterers. Optical reflectance measurements, magneto-optical Kerr effect spectra, andfinite-difference time-domain simulations confirm the analytical results. Hybrid dimer arrays supporting intense plasmonexcitations are a promising candidate for active magnetoplasmonic devices. [less ▲]

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See detailSite-Selective Integration of MoS2 Flakes on Nanopores by Means of Electrophoretic Deposition
Mosconi, Dario; Giovannini, Giorgia; Jacassi, Andrea et al

in ACS Omega (2019), 4(5), 9294-9300

Here, we propose an easy method for site-selective deposition of two-dimensional (2D) material flakes onto nanoholes by means of electrophoretic deposition. This method can be applied to both simple flat ... [more ▼]

Here, we propose an easy method for site-selective deposition of two-dimensional (2D) material flakes onto nanoholes by means of electrophoretic deposition. This method can be applied to both simple flat nanostructures and complex three-dimensional structures incorporating nano- holes. The deposition method is here used for the decoration of large ordered arrays of plasmonic structures with either a single or few layers of MoS2 . In principle, the plasmonic field generated by the nanohole can significantly interact with the 2D layer leading to enhanced light−material interaction. This makes our platform an ideal system for hybrid 2D material/ plasmonic investigations. The engineered deposition of 2D materials on plasmonic nanostructures is useful for several important applications such as enhanced light emission, strong coupling, hot-electron generation, and 2D material sensors. Site-selective integration of MoS2 flakes on nanopores by means of electrophoretic deposition. [less ▲]

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See detailHybrid Ni/SiO2/Au dimer arrays for high-resolution refractive index sensing
Pourjamal, Sara; Kataja, Mikko; Maccaferri, Nicolò UL et al

in Nanophotonics (2018), 7(5), 905-912

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 direr nanodisks. Combined effects of near ... [more ▼]

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 direr 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. [less ▲]

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See detailMagnetic Control of the Chiroptical Plasmonic Surfaces
Zubritskaya, Irina; Maccaferri, Nicolò UL; Inchausti Ezeiza, Xabier et al

in Nano Letters (2018), 18(1), 302-307

A major challenge facing plasmon nanophotonics is the poor dynamic tunability. A functional nanophotonic element would feature the real-time sizable tunability of transmission, reflection of light's ... [more ▼]

A major challenge facing plasmon nanophotonics is the poor dynamic tunability. A functional nanophotonic element would feature the real-time sizable tunability of transmission, reflection of light's intensity or polarization over a broad range of wavelengths, and would be robust and easy to integrate. Several approaches have been explored so far including mechanical deformation, thermal, or refractive index effects, and all-optical switching. Here we devise an ultrathin chiroptical surface, built on two-dimensional nanoantennas, where the chiral light transmission is controlled by the externally applied magnetic field. The magnetic field-induced modulation of the far-field chiroptical response with this surface exceeds 100% in the visible and near-infrared spectral ranges, opening the route for nanometer-thin magnetoplasmonic light-modulating surfaces tuned in real time and featuring a broad spectral response. [less ▲]

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See detailHybrid plasmonic lattices with tunable magneto-optical activity
Kataja, Mikko; Pourjamal, Sara; Maccaferri, Nicolò UL et al

in Optics Express (2016), 24(4), 3652-3662

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 ... [more ▼]

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. [less ▲]

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See detailAnisotropic Nanoantenna-Based Magnetoplasmonic Crystals for Highly Enhanced and Tunable Magneto-Optical Activity
Maccaferri, Nicolò UL; Bergamini, Luca; Pancaldi, Matteo et al

in Nano Letters (2016), 16(4), 2533-2542

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 ... [more ▼]

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. [less ▲]

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See detailPolarization conversion-based molecular sensing using anisotropic plasmonic metasurfaces
Verre, Ruggero; Maccaferri, Nicolò UL; Fleischer, Karsten et al

in Nanoscale (2016), 8(20), 10576-10581

Anisotropic media induce changes in the polarization state of transmitted and reflected light. Here we combine this effect with the refractive index sensitivity typical of plasmonic nanoparticles to ... [more ▼]

Anisotropic media induce changes in the polarization state of transmitted and reflected light. Here we combine this effect with the refractive index sensitivity typical of plasmonic nanoparticles to experimentally demonstrate self-referenced single wavelength refractometric sensing based on polarization conversion. We fabricated anisotropic plasmonic metasurfaces composed of gold dimers and, as a proof of principle, measured the changes in the rotation of light polarization induced by biomolecular adsorption with a surface sensitivity of 0.2 ng cm−2. We demonstrate the possibility of miniaturized sensing and we show that experimental results can be reproduced by analytical theory. Various ways to increase the sensitivity and applicability of the sensing scheme are discussed. [less ▲]

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See detailMagnetoplasmonic crystals based on anisotropic nanoantennas
Bergamini, Luca; Maccaferri, Nicolo UL; Pancaldi, Matteo et al

in Conference on Lasers and Electro-Optics (2016)

By synergically combining experiments and simulations, we show how the excitation of lattice surface modes in ordered arrays of magnetic and optically-anisotropic nanoantennas leads to a highly enhanced ... [more ▼]

By synergically combining experiments and simulations, we show how the excitation of lattice surface modes in ordered arrays of magnetic and optically-anisotropic nanoantennas leads to a highly enhanced and tunable Fano-like modulation of the magneto-plasmonic response. [less ▲]

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See detailResonant Enhancement of Magneto-Optical Activity Induced by Surface Plasmon Polariton Modes Coupling in 2D Magnetoplasmonic Crystals
Maccaferri, Nicolò UL; Inchausti, Xabier; Garcia-Martin, Antonio et al

in ACS Photonics (2015), 2(12), 1769-1779

Magnetoplasmonic crystals are spatially periodic nanostructured magnetic surfaces combining the features of surface plasmon polariton excitation and magneto-optical tunability. Here we present a ... [more ▼]

Magnetoplasmonic crystals are spatially periodic nanostructured magnetic surfaces combining the features of surface plasmon polariton excitation and magneto-optical tunability. Here we present a comprehensive experimental and theoretical work demonstrating that in magnetoplasmonic crystals the coupling of free space radiation to surface plasmon polariton modes in conjunction with the inherent magneto-optical activity, enable cross-coupling of propagating surface plasmon polariton modes. We have explored the consequences of this unique magnetoplasmonic crystal optical feature by studying the light reflected from a two-dimensional periodic array of cylindrical holes in a ferromagnetic layer illuminated at oblique incidence and magnetized in the sample plane, namely, in the so-called longitudinal Kerr effect geometry. We observe that the magneto-optical spectral response arises from all the excitable surface plasmon polariton modes in the magnetoplasmonic crystal irrespective of the incoming light polarization. We show that this is a direct consequence of the magneto-optically mediated coupling of propagating surface plasmon polariton modes. We demonstrate that a large enhancement of the longitudinal Kerr effect is induced when special noncollinear surface plasmon polariton modes, which couple to both p- and s-polarized light, are resonantly excited. We show how the resonant enhancement of the Kerr effect can be set at desired radiation wavelengths and incidence angles by precise plasmonic band engineering achievable through the proper design of the magnetoplasmonic lattice structure. Our findings, besides clarifying the underlying physics that governs the peculiar magneto-optical properties of magnetoplasmonic crystals, open a path to the design of novel active metamaterials with tailored and enhanced magneto-optical activity. [less ▲]

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See detailActive Magnetoplasmonic Ruler
Zubritskaya, Irina; Lodewijks, Kristof; Maccaferri, Nicolò UL et al

in Nano Letters (2015), 15(5), 3204-3211

Plasmon rulers are an emerging concept in which the strong near-field coupling of plasmon nanoantenna elements is employed to obtain structural information at the nanoscale. Here, we combine ... [more ▼]

Plasmon rulers are an emerging concept in which the strong near-field coupling of plasmon nanoantenna elements is employed to obtain structural information at the nanoscale. Here, we combine nanoplasmonics and nanomagnetism to conceptualize a magnetoplasmonic dimer nanoantenna that would be able to report nanoscale distances while optimizing its own spatial orientation. The latter constitutes an active operation in which a dynamically optimized optical response per measured unit length allows for the measurement of small and large nanoscale distances with about 2 orders of magnitude higher precision than current state-of-the-art plasmon rulers. We further propose a concept to optically measure the nanoscale response to the controlled application of force with a magnetic field. [less ▲]

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See detailUltrasensitive and label-free molecular-level detection enabled by light phase control in magnetoplasmonic nanoantennas
Maccaferri, Nicolò UL; Gregorczyk, Keith E.; de Oliveira, Thales V. A. G. et al

in Nature Communications (2015), 6

Systems allowing label-free molecular detection are expected to have enormous impact on biochemical sciences. Research focuses on materials and technologies based on exploiting localized surface plasmon ... [more ▼]

Systems allowing label-free molecular detection are expected to have enormous impact on biochemical sciences. Research focuses on materials and technologies based on exploiting localized surface plasmon resonances in metallic nanostructures. The reason for this focused attention is their suitability for single-molecule sensing, arising from intrinsically nanoscopic sensing volume and the high sensitivity to the local environment. Here we propose an alternative route, which enables radically improved sensitivity compared with recently reported plasmon-based sensors. Such high sensitivity is achieved by exploiting the control of the phase of light in magnetoplasmonic nanoantennas. We demonstrate a manifold improvement of refractometric sensing figure-of-merit. Most remarkably, we show a raw surface sensitivity (that is, without applying fitting procedures) of two orders of magnitude higher than the current values reported for nanoplasmonic sensors. Such sensitivity corresponds to a mass of ~ 0.8 ag per nanoantenna of polyamide-6.6 (n=1.51), which is representative for a large variety of polymers, peptides and proteins. [less ▲]

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See detailEffects of a non-absorbing substrate on the magneto-optical Kerr response of plasmonic ferromagnetic nanodisks
Maccaferri, Nicolò UL; Kataja, Mikko; Bonanni, Valentina et al

in Physica Status Solidi A. Applications and Materials Science (2014), 211(5), 1067-1075

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 ... [more ▼]

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. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim [less ▲]

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See detailMagnetoplasmonic Design Rules for Active Magneto-Optics
Lodewijks, Kristof; Maccaferri, Nicolò UL; Pakizeh, Tavakol et al

in Nano Letters (2014), 14(12), 7207-7214

Light polarization rotators and nonreciprocal optical isolators are essential building blocks in photonics technology. These macroscopic passive devices are commonly based on magneto-optical Faraday and ... [more ▼]

Light polarization rotators and nonreciprocal optical isolators are essential building blocks in photonics technology. These macroscopic passive devices are commonly based on magneto-optical Faraday and Kerr polarization rotation. Magnetoplasmonics, the combination of magnetism and plasmonics, is a promising route to bring these devices to the nanoscale. We introduce design rules for highly tunable active magnetoplasmonic elements in which we can tailor the amplitude and sign of the Kerr response over a broad spectral range. [less ▲]

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See detailTuning the Magneto-Optical Response of Nanosize Ferromagnetic Ni Disks Using the Phase of Localized Plasmons
Maccaferri, Nicolò UL; Berger, Andreas; Bonetti, Stefano et al

in Physical Review Letters (2013), 111(16), 167401

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 ... [more ▼]

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. [less ▲]

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See detailPolarizability and magnetoplasmonic properties of magnetic general nanoellipsoids.
Maccaferri, Nicolò UL; Gonzalez-Diaz, Juan B.; Bonetti, Stefano et al

in Optics Express (2013), 21(8), 9875-9889

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 ... [more ▼]

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. [less ▲]

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