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We demonstrate a novel all-dielectric magnetophotonic structure that consists of two-dimensional arrays of bismuth substituted iron-garnet nanocylinders supporting both localized (Fabry–Perot-like) and lattice (guided-like) optical modes. Simultaneous excitation of the two kinds of modes provides a significant enhancement of the Faraday effect by 3 times and transverse magneto-optical Kerr effect by an order of magnitude compared to the smooth magnetic film of the same effective thickness. Both magneto-optical effects are boosted in wide spectral and angular ranges making the nanocylinder array magnetic dielectric structures promising for applications with short and tightly focused laser pulses.

Graphene is a unique material in the study of the fundamental limits of plasmonics. Apart from the ultimate single-layer thickness, its carrier concentration can be tuned by chemical doping or applying an electric field. In this manner, the electrodynamic properties of graphene can be varied from highly conductive to dielectric. Graphene supports strongly confined, propagating surface plasmon polaritons (SPPs) in a broad spectral range from terahertz to mid-infrared frequencies. It also possesses a strong magneto-optical response and thus provides complimentary architectures to conventional magneto-plasmonics based on magneto-optically active metals or dielectrics. Despite a large number of review articles devoted to plasmonic properties and applications of graphene, little is known about graphene magneto-plasmonics and topological effects in graphene-based nanostructures, which represent the main subject of this review. We discuss several strategies to enhance plasmonic effects in topologically distinct closed surface landscapes, i.e. graphene nanotubes, cylindrical nanocavities and toroidal nanostructures. A novel phenomenon of the strongly asymmetric SPP propagation on chiral meta-structures and the fundamental relations between structural and plasmonic topological indices are reviewed.

Interaction between light and magnetism in magneto-optical (MO) nanophotonic devices has been actively studied in the past few years. The recent development of MO all-dielectric resonators and metasurfaces has led to the emergence of various novel MO phenomena that were not observed in their bulk counterparts. For example, a large s-polarized transverse MO Kerr effect can be observed at magnetic resonance wavelength, which cannot exist in the bare MO films. We review recent developments in nanophotonic devices based on MO materials and focus on different modes and related MO effects in nanophotonic structures with emphasis on recently discovered new MO phenomena in magnetoplasmonics and all-dielectric nanostructures, such as dark mode, all-dielectric Mie resonance and waveguide mode. Further, we discuss the potential applications of these nanostructures for biological/chemical sensing, magnetic field sensing, and magnetic field-controlled active and nonreciprocal metasurfaces.

In this study, we propose and simulate a magnetoplasmonics heterostructure that utilizes spin–orbit fields to generate an internal magnetic field and create a significant magneto-optical effect. Our approach offers a new way to overcome the challenges of using permanent magnets or magnetic coils in conventional magnetoplasmonics, such as high-power consumption and non-scalability. We demonstrate that it is possible to create an appropriate amount of magnetic field using spin–orbit fields induced by the spin-Hall effect, such that the consumption power becomes reasonable and the dimensions could be miniaturized. This approach will be an important development in the field of magneto-optics, as it can lead to enhanced transverse magneto-optical Kerr effect in the present of surface plasmon polaritons. The proposed nanostructure consists of a ferromagnetic film adjacent to a heavy metal layer, both sandwiched between two noble metal films, and deposited on a dielectric prism. The strength of the Kerr signal strongly depends on the thickness of the ferromagnetic layer, with the maximum effect observed at a thickness of 5nm. This concept has potential for various nanophotonic and spintronic applications, particularly for developing high-speed active plasmonic devices for ultrafast light modulation.

Polarization and related spin properties are important characteristics of electromagnetic waves and their manipulation is crucial in almost all photonic applications. Magnetic materials are often used for controlling light polarization through the magneto-optical Kerr or Faraday effects. Recently, complex topological structures of the optical spin have been demonstrated in the evanescent light field, which in the presence of the spin–orbit coupling may form photonic skyrmions. Here, we investigate the optical spin–orbit coupling in the presence of magnetization and the interaction between photonic skyrmions and magnetic domains. We demonstrate that the magnetization is responsible for the modulation of the optical spin distribution, resulting in twisted Neel-type skyrmions. This effect can be used for the visualization of magnetic domain structure with both in plane and polar orientation of magnetization, and in turn for creation of complex optical spin distributions using magnetization patterns. The demonstrated interplay between photonic skyrmions and magneto-optical effects may also provide novel opportunities for investigation and manipulation of magnetic skyrmions using optical spin–orbit coupling.

Magnet‐optical materials embracing coupled magnetic and photoluminescent properties in single phase are promising in microelectronics and optoelectronic devices. However, the current research mainly focuses on traditional inorganic materials, and there are few reports on molecule materials. Recently, we synthesized an organic–inorganic hybrid complex (C6H5C2H3FNH3)2MnCl4 (1) with perovskite structure. Physical measurements show that 1 not only behaves as an antiferromagnet with spin canting but also exhibits unusual fluorescent properties. Importantly, under the magnetic field at different temperatures, the luminous intensity of 1 changed, and a red‐shift occurred with obviously optical hysteresis. These phenomena directly prove the existence of magneto‐optical coupling in 1. More interestingly, the optical hysteresis can be observed in both low and high field, which is unprecedented in other molecular materials. Even in traditional inorganic materials, it can only be observed in strong field. This special function provides the possibility for the application of low energy consumption optoelectronic devices. This is the first coordination complex showing magneto‐luminescence. Besides, under different temperatures and applied magnetic fields, the title complex exhibits the unusual magneto‐fluorescence properties, in which the emission peak has an obvious red‐shift with the increasing magnetic field with a hysteresis loop even in low field. This special phenomenon provides the possibility for the application of low energy consumption optoelectronic devices.

To realize nonreciprocal transmission, it is necessary to break the time-reversal symmetry of the transmission system, but it is very challenging to keep the linear polarized (LP) input and output unchanged in the free space transmission system. Magnetized semiconductor InSb can realize terahertz (THz) nonreciprocal transmission for the two conjugated photonic spin states, but it cannot realize efficient one-way transmission of LP state due to gyro-mirror symmetry. In this work, by introducing a pair of orthogonal uniaxial anisotropies from the meta-gratings on both sides of InSb, both the gyro-mirror and time-reversal symmetries are broken for the LP state, thus making this cascaded grating–InSb–grating structure serves as a high-performance isolator for the LP light. The experiment results indicate isolation of 50 dB at 0.4 THz for the same LP input and output under a weak biased magnetic field of 0.17 T. Moreover, we further illustrate the factors affecting the isolation bandwidth of the device, also demonstrated another broadband structure with the 10 dB isolation bandwidth from 0.2–0.7 THz, and the relative bandwidth achieves 110%. The mechanisms of THz nonreciprocal transmission and polarization manipulation proposed in this work will contribute to the development of efficient THz magneto-optical devices.

Recently, two-dimensional (2D) GaS and GaSe nanosheets were successfully fabricated and the measured electronic, mechanical, and optoelectronic properties are excellent. Here, using the first-principles density functional theory, we investigate the magnetic, optical, and magneto-optical (MO) Kerr and Faraday effects in hole-doped GaS and GaSe multilayers. GaS and GaSe monolayers (MLs) manifest ferromagnetic ground states by introducing even a small amount of hole doping, whereas the magnetism in GaS and GaSe multilayers are significantly different under hole doping. Our results show that ferromagnetic states can be easily established in GaS bilayers and trilayers under proper hole doping, however, most of GaSe multilayers are more favorable to nonmagnetic states. The magnetic moments in GaS multilayers are weakened remarkably with the increasing of thin film thickness and are negligible more than three MLs. This leads to the thickness dependence of MO Kerr and Faraday effects. Furthermore, the MO effects strongly depend on the doping concentration and therefore are electrically controllable by adjusting the number of holes via gate voltage. The substrate effects on the MO properties are also discussed. Combining the unique MO and other interesting physical properties make GaS and GaSe a superior 2D material platform for semiconductor MO and spintronic nanodevices.

The latest discovery of ferromagnetism in atomically thin films of semiconductors Cr2Ge2Te6 and CrI3 has unleashed numerous opportunities for fundamental physics of magnetism in two-dimensional (2D) limit and also for technological applications based on 2D magnetic materials. To exploit these 2D magnetic materials, however, the mechanisms that control their physical properties should be thoroughly understood. In this paper, we present a comprehensive theoretical study of the magnetic, electronic, optical and magneto-optical (MO) properties of multilayers (monolayer (ML), bilayer (BL) and trilayer) as well as bulk CrI3, based on the density functional theory with the generalized gradient approximation plus on-site Coulomb repulsion scheme. Interestingly, all the structures except the BL, are found to be single-spin ferromagnetic semiconductors. They all have a large out-of-plane magnetic anisotropy energy (MAE) of ∼0.5 meV/Cr, in contrast to the significantly thickness-dependent MAE in multilayers of Cr2Ge2Te6. These large MAEs suppress transverse spin fluctuations and thus stabilize long-range magnetic orders at finite temperatures down to the ML limit. They also exhibit strong MO effects with their Kerr and Faraday rotation angles being comparable to that of best-known bulk MO materials. The shape and position of the main features in the optical and MO spectra are found to be nearly thickness-independent although the magnitude of Kerr rotation angles increases monotonically with the film thickness. Magnetic transition temperatures estimated based on calculated exchange coupling parameters, calculated optical conductivity spectra, MO Kerr and Faraday rotation angles agree quite well with available experimental data. The calculated MAE as well as optical and MO properties are analyzed in terms of the calculated orbital-decomposed densities of states, band state symmetries and dipole selection rules. Our findings of large out-of-plane MAEs and strong MO effects in these single-spin ferromagnetic semiconducting CrI3 ultrathin films suggest that they will find valuable applications in semiconductor MO and spintronic nanodevices.

We report image classification using a diffractive neural network based on the magneto-optical effect (MO-DNN). Diffractive neural networks (DNNs) offer unique advantages such as low power consumption, high-speed computing, and parallel processing. The incorporation of the MO effect into DNNs introduces reconfigurability, nonvolatility, and the potential for compact devices. However, the phase modulation achievable with MO materials is typically smaller than that achievable with liquid crystals. In this study, we focused on the 90° polarization rotation of diffracted light induced by the MO effect and found that an MO-DNN with a single hidden layer and a polarizer achieved 98% classification accuracy for the MNIST handwritten digit dataset. The MO-DNN was physically implemented using a bismuth, gallium-substituted garnet film as the MO medium and a thermomagnetic recording technique. Its performance was demonstrated experimentally with a classification accuracy of 83%, and task switching was achieved by rewriting the MO hidden layer. The MO-DNN demonstrates strong potential for realizing compact, reconfigurable, and energy-efficient photonic computing devices integrated with image sensors.