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CIC01_Master_Nanostructured magnetic metamaterials for light manipulation at the nanoscale

SUITABLE FOR physicists, materials scientists, engineers

In the last decade, and driven by the strong development of nanotechnology, there has been an increased interest in the study of the optical properties of metallic nanostructures and nanoparticles and their ability to control and manipulate light. In particular, it was found that tailor designed nanostructured materials offers the possibility to control propagation, localization, and polarization of light at the nanoscale and beyond the intrinsic properties of the constituent material. A current focal point of research is, thereby, the development of novel nanostructured composite materials (metamaterials) with “designed” and tunable optical properties. These novel materials exploit the capability of metallic nanoparticles to confine the electromagnetic (EM) field beyond the diffraction limit when properly excited by the electromagnetic field of a light beam impinging on them (plasmon resonance). This property offers a way to beat the light diffraction limit and enable a path towards subwavelength optics to be used to develop nano-photonics devices. Equivalently interesting, is the strong dependence of this EM field confinement effect on the environment that offers a clear pathway to the development of ultrasensitive (at the single molecule level) sensors for environmental and biological applications.

Particularly interesting are composite metamaterials made of ferromagnetic nanoelements because they combine the plasmonic behavior described above with intertwined optical and magnetic properties (magneto-optical activity, see Fig. 1) [1-4]. Such multifunctional magneto-plasmonic metamaterials may open new views towards applications to variety of emerging technologies as, e.g., magnetoplasmonic rulers (dimers that are able to report the nanoscale distances) [5], ultrasensitive molecular sensing (see Fig. 2) [6,10] and ultrathin optical metadevices (flat nano-optics) [7-9].

The goal of the present master/PhD project is the experimental exploration and control of the mutual relations between magnetism and optical properties of ferromagnetic composite metamaterials combining MO-activity and plasmonic behavior. To this purpose, laser-based measurement spectrometers that measure light intensity/polarization and intensity/polarization changes with a very high degree of precision are required. One such example is the experimental MOKE (Magneto Optical Kerr Effect) spectrometer (SpectroMOKE) at nanoGUNE that measures light intensity/polarization changes, which are caused by the magnetic properties of materials, including arrays of magnetic nano-objects, in the spectral region from 400 to 1800 nm.

The spectroMOKE set-up will be utilized to measure the optical and MO spectral response of metamaterials made of ferromagnetic-alloys and multilayered nano-structures of several sizes and shape deposited on a dielectric substrate, that will be also fabricated in our laboratory. The acquired data will then be analyzed using advanced modeling tools based on electromagnetic theory, which has been specifically devised to deal with nano-scale optical objects.

Figure 1

Fig. 1: Electromagnetic field confinement effect due to the excitation of a localized plasmon in a metallic nanostructure; (central panel) example of a nanofotonic device for light polarization manipulation.

Figure 2

Fig. 2: Light polarization manipulation enabled by phase compensation in the optical response of a magneto-plasmonic Ni nanoantenna and its exploitation for ultrasensitive sensing.

References and reading list

  • J. Chen et al., Small 7, 2341 (2011)
  • V. Bonanni et al., Nano Lett. 11, 5333 (2011)
  • N. Maccaferri et al., Phys. Rev. Lett. 111, 167401 (2013)
  • N. Maccaferri et al., Opt. Express 21, 9875 (2013)
  • I. Zubritskaya et al., Nano Lett. 15, 3204 (2015)
  • N. Maccaferri et al., Nature Commun. 6, 6150 (2015)
  • K. Lodewijks et al., Nano Lett. 14, 7207 (2014)
  • M. Kataia et al., Nature Commun. 6, 7072 (2015)
  • N. Maccaferri et al., Nano Lett. 16, 2533 (2016)
  • R. Verre et al., Nanoscale 8, 10576 (2016)

More information: Nanomagnetism Group

E-mail: p.vavassori@nanogune.eu

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