Coupling phenomena and collective effects in resonant meta-atoms supporting both plasmonic and (opto-)magnetic functionalities: an overview on properties and applications [Invited]

Abstract

We review both the fundamental aspects and the applications of functional magneto-optic and opto-magnetic metamaterials displaying collective and coupling effects on the nanoscale, where the concepts of optics and magnetism merge to produce unconventional phenomena. The use of magnetic materials instead of the usual noble metals allows for an additional degree of freedom for the control of electromagnetic field properties, as well as it allows light to interact with the spins of the electrons and to actively manipulate the magnetic properties of such nanomaterials. In this context, we explore the concepts of near-field coupling of plasmon modes in magnetic meta-molecules, as well as the effect of excitation of surface lattice resonances in magneto-plasmonic crystals. Moreover, we discuss how these coupling effects can be exploited to artificially enhance optical magnetism in plasmonic meta-molecules and crystals. Finally, we highlight some of the present challenges and provide a perspective on future directions of the research towards photon-driven fast and efficient nanotechnologies bridging magnetism and optics beyond current limits.

Nanoscale magnetophotonics

“…In this case the MO properties are due to Lorentz force acting on free electrons in a magnetic field. A resonant increase of the T- 11 MOKE was reported for one-dimensional Co, Fe and Ni gratings [69,70]. Pronounced resonance of T-MOKE in a sample of 1D trilayer SiO2/Fe/Ag MPC fabricated on a commercial blue-ray disc also allowed to consider a refractive index sensor on its basis [71] The MPC structures can also be referred as magnetophotonic metasurfaces, though the term of metasurface is more general and also includes all-dielectric and semiconductor materials consisting of substrates covered with cylinders and spheres sustaining Mie resonances [80,81].…”

Active photonic platforms for the mid-infrared to the THz regime using spintronic structures

“…Besides, it has been shown that the MO activity of magnetoplasmonic structures can be enhanced by putting the MO active material at particular places within the structure [121,122]. On the other hand, metamaterials structures have shown their ability to design tailored electromagnetic fields in a very wide spectral range [123], and resonant meta-atoms with both plasmonic and (opto)-magnetic functionalities have shown great potential [124]. Therefore, exploring the use of metamaterials to maximize the electromagnetic field at the position of the spintronic component may be a way to further improve the performance of MRE based photonic platforms.…”

Synthetic Approaches to Colloidal Nanocrystal Heterostructures Based on Metal and Metal-Oxide Materials

“…Moreover, while a metal or semiconductor domain in a CNHS can permit its identification optically, a magnetic module can be exploited for supplemental purposes, such as for MRI imaging and magnetic sorting [ 22 , 23 , 24 , 25 , 212 , 213 , 214 , 215 , 216 , 217 , 218 , 219 , 220 ]. Interestingly, in a CNHS, synergistic interactions setting through the heterointerfaces between the component materials can result in significantly altered magnetic [ 38 , 101 , 102 , 220 , 221 , 222 , 223 , 224 , 225 ], optical [ 226 , 227 , 228 ], transport [ 221 ], magneto-optical [ 39 , 40 , 41 , 42 , 43 , 44 , 229 ], and (electro)catalytic [ 230 , 231 , 232 , 233 , 234 , 235 , 236 , 237 , 238 , 239 ] properties, as well as energy-storing capabilities [ 240 ]. Such wealth of chemical-physical behaviour has both...…”

“…For example, CNHSs based on semiconductors and/or metals frequently show anomalous optical absorption and/or emission and/or conductivity due to induced modifications in electronic structure, quantum confinement, charge-carrier dynamics, and/or induction of strong plasmon-exciton coupling [ 32 , 34 , 35 , 36 ]. In CNHSs that incorporate noble metals and magnetic materials, the synergistic interplay of magnetic, magneto-optical, and surface plasmon resonance features may lead to unusually altered or mutually switchable magnetic and optical properties through interesting, yet poorly understood exchange-interaction mechanisms [ 5 , 22 , 27 , 28 , 29 , 38 , 39 , 40 , 41 , 42 , 43 , 44 ]. Alterations in electronic structure, the introduction of heterojunctions, and the establishment of predesigned charge-carrier transfer pathways across calibrated potential profiles have been exploited to manipulate the performances of catalytically and (photo)catalytically active CNHSs [ 36 , 45 , 46 , 47 , 48 ].…”