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The optical effects of dichroism, static light scattering, and light attenuation under the action of a magnetic field in magnetic fluids with an average particle size of 6.7 and 13.7 nm were studied. Significant differences were found both in the magnitude of the effects and in their spectral behavior. They can be due to the formation of aggregates in the sample with larger particles, which significantly change the optical properties of the system. The formation of aggregates under the action of the field was confirmed by dynamic light scattering. [ABSTRACT FROM AUTHOR]

Directional control of far‐field thermal emission plays a key role in effective heat and energy transfer. However, conventional photonic strategies are challenging to concurrently control the polar and azimuthal angle of thermal emission over broadband. Here both polar and azimuthal angles of thermal emission are constrained to narrow ranges over broadband by introducing in‐plane anisotropy combined with magneto‐optical materials in the epsilon‐near‐zero (ENZ) wavelength range. The physical mechanism of tunable perfect absorption/emission is explored by investigating the evolution of multiple topological phase singularity pairs (TPSPs). The structure consisting of a magnetized gradient‐ENZ emitter and anisotropic spacer that exhibits high (>0.8) unidirectional emissivity (θ: 55°–79°, φ: 163.5°–196.5°) in the p‐polarization for a broad range of wavelength (22–26 µm) is demonstrated. The unveiled physics synergizing ENZ, anisotropy, and magneto‐optical properties that support broadband unidirectional thermal emission will bring new opportunities in applications such as thermal camouflaging, thermal photovoltaics, and infrared light sources. [ABSTRACT FROM AUTHOR]

In this work we demonstrate the fabrication protocol of 2D-magnetoplasmonic crystals consisting of permalloy column arrays. Dependences of morphological, magnetic, optical, and magneto-optical properties of 2D-magnetoplasmonic crystals on the e-beam exposition dose are studied. Proposed protocol is suitable for the fabrication of 2D-structures with controllable dimensions and morphology of individual columns having substantial potential for applications as sensitive magnetic field probes. [ABSTRACT FROM AUTHOR]

Light propagation through magnetic media with ellipsoidal inclusions much smaller than the light wavelength was investigated theoretically. It is assumed that the ellipsoidal inclusions have the same orientation but are randomly distributed inside the magnetic medium by the Gaussian law. The theoretical model is based on the multiple-scattering theory in the ladder approximation. A new type of electromagnetic field correlation is found to appear in this case, while it is absent in isotropic magnetic nanocomposites and nonmagnetic anisotropic composites. This feature allows for the precise control of light polarization in anisotropic magnetic media.

Light propagation through magnetic media with ellipsoidal inclusions much smaller than the light wavelength was investigated theoretically. It is assumed that the ellipsoidal inclusions have the same orientation but are randomly distributed inside the magnetic medium by the Gaussian law. The theoretical model is based on the multiple-scattering theory in the ladder approximation. A new type of electromagnetic field correlation is found to appear in this case, while it is absent in isotropic magnetic nanocomposites and nonmagnetic anisotropic composites. This feature allows for the precise control of light polarization in anisotropic magnetic media. [ABSTRACT FROM AUTHOR]

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.

We show theoretically that the enhanced optical chirality in the achiral magnetoplasmonic nanostructures including dual-metallic grating (DMG) structure and single-metallic grating (SMG) structure under linearly polarized light can be achieved. The simulated results, based on the extended finite difference time domain (EFDTD) method, show that the designed structures possess the enhanced optical chirality in the visible and near-infrared wavelengths. More importantly, although the magnetoplasmonic nanostructure with DMG structure possesses an easy fabrication process, its performance of optical chirality is superior to that of the SMG structure. The physical origin of the enhanced optical chirality is deeply researched in detail. We also show that the optical chirality can be adjusted by the external magnetic field, which denotes that the magnetoplasmonic nanostructures will be used to develop a new chiro-optical device. [ABSTRACT FROM AUTHOR]

In this article we introduce a magnetoplasmonics (MP) planar nanostructure with enhanced transverse magneto-optical (MO) activity. For this goal MO characteristics of magneto-structures containing both metal layer and linear array of (metal) nanorods are analyzed. We explore three types of structures with nanorods and compare their features based on transvers magneto-optical Kerr effect (TMOKE) with the corresponding one for conventional three layers MO structure. Comparison between the values of TMOKE signals in two structures (proposed and conventional) shows more than one order of magnitude improvement. Accordingly, the refractive index sensitivity of the offered structures, specially with one and three types of Au nanorod arrays, appearance more than 2 order of magnitude larger than the conventional Au/Co/Au three layer MO structures. This notable response enhancement becomes serious affair in MP biosensing applications. We believe that our idea in these proposed nanostructures can be used in any other three layer based MO structures in the literature. On this basis, we apply this scenario to other types of such MO structures which leads to improvement in their MO activities and whereupon in their refractive index sensitivities. [ABSTRACT FROM AUTHOR]

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.

Spectral dependences of birefringence and dichroism in magnetic colloids of magnetite nanoparticles have been studied. The results demonstrate that previously reported spectra of the refractive index of bulk magnetite are poorly suited for quantitative and qualitative interpretation of optical effects in magnetic fluids. Data on magneto-optical effects in magnetic colloids have been used to determine spectra of the real and imaginary parts of the refractive index of nanoparticulate magnetite in the wavelength range 400–1050 nm. [ABSTRACT FROM AUTHOR]

Magneto-optical effects (MOE), interfacing the fundamental interplay between magnetism and light, have served as a powerful probe for magnetic order, band topology, and valley index. Here, based on multiferroic and topological bilayer antiferromagnets (AFMs), we propose a layer control of MOE (L-MOE), which is created and annihilated by layer-stacking or an electric field effect. The key character of L-MOE is the sign-reversible response controlled by ferroelectric polarization, the Néel vector, or the electric field direction. Moreover, the sign-reversible L-MOE can be quantized in topologically insulating AFMs. We reveal that the switchable L-MOE originates from the combined contributions of spin-conserving and spin-flip interband transitions in spin-valley splitting AFMs, a phenomenon not observed in conventional AFMs. Our findings bridge the ancient MOE to the emergent realms of layertronics, valleytronics, and multiferroics and may hold immense potential in these fields.

The II-VI based magnetic semiconductors with a direct and wide optical bandgap are expected to show high potential for optical applications utilizing short wavelength laser diodes (LDs), such as 532-nm green and 475-nm blue LDs. We have confirmed that the Faraday rotation θF in the ZnMnTe and ZnMnSe films deposited on quartz glass (QG) and sapphire (SA) substrates by using molecular beam epitaxy (MBE) is large near the absorption edge. This paper reports the magneto-optical properties of ZnMnTe and ZnMnSe films synthesized on the QG and SA substrates, and shows the result of a direct Faraday rotation observation successfully made for the ZnMnTe films under 1.28-kHz alternating magnetic fields. The optical absorption characteristics of the ZnMnTe films grown on the SA substrates by MBE are discussed by comparing them with the optical absorption properties and photoluminescence spectra of the II-VI ZnTe parent single crystals.

Nitrogen‐vacancy (NV) colour centres in diamond have attracted extensive attention in quantum precision measurement, computation and communication. In these fields, microwave manipulation is a technology in which antenna is used to radiate special microwave to manipulate the quantum spin state of NV colour centres. In this work, high frequency structure simulator software is used to design a microstrip antenna with a resonance frequency of 2.8756 GHz. Based on simulation and experiments, near field radiation of antenna is optimised to improve its microwave manipulation quality. This antenna will be helpful in the development of hybrid quantum devices of NV centres. [ABSTRACT FROM AUTHOR]

Light localization by metal particles of nanometer size allows to not only control the propagation of light, but also enhance magneto‐optical effects. The influence of the immersion of gold nanodisks inside a transparent magnetic medium, namely, Bi‐substituted iron garnet, is investigated, and the optimal position of the nanoparticles within the magnetic material for a strong enhancement of the effect is unraveled. Three samples with periodic arrays of Au cylinders are studied: disks on the surface of the magnetic dielectric film, inside the magnetic film, and directly under the magnetic film. The largest enhancement of the Faraday effect mediated by a localized surface plasmon resonance takes place when nanodisks are submerged inside the magnetic film at a few nanometers below its upper surface. It is shown that the most prominent influence on the Faraday effect enhancement is provided by the magnetic medium between the nanodisks. The experimental results are in good agreement with the numerical analysis. [ABSTRACT FROM AUTHOR]

As the absolute magneto-optical effect of transition metal dichalcogenides (TMDC) was weak, its practical application in magneto-optical devices was affected. In this study, three kinds of composite structures composed of monolayer TMDC and SiC were proposed. Their Faraday rotation (FR) angles and transmittance were calculated by the transmission matrix method. The results show that the three composite structures can improve the magneto-optical properties. Compared with the double-layer structure composed of monolayer TMDC and SiC substrate, the symmetrical composite structure obtains eight times FR angle enhancement and 0.8 transmittance at the working frequency, and the composite structure also achieves a certain degree of broadband magneto-optical effect enhancement. Through the analysis of the field distribution and simulation results, it is proved that the composite structure with multiple monolayer TMDC can achieve the broadband magneto-optical effect enhancement and high transmittance at the same time. [ABSTRACT FROM AUTHOR]

A study is performed of the spatial distribution of magnetic field of a microelectromechanical systems (MEMS) with the aid of magneto-optical indicator ferrite garnet films (MOIF). In order to increase the accuracy and the dynamic range of measure a procedure was developed including the use of auxiliary external field resulting in a controlled shift of the zero-field lines. In this case the MOIF serves as a null-indicator eliminating the dependence of the measuring results on the specific transfer parameters (linearity characteristics). Imposition of biasing field provides a possibility of shifting the saturation threshold field of the MOIF either in the region of positive or negative values.

The results of synthesis and experimental study of two types of nanocomposites based on Au/Ni nanorods in porous anodic alumina matrix are presented. The existence of two features in the optical spectra of such structures corresponding epsilon-near-zero and epsilon-near-pole points is shown. A significant modulation and enhancement of the alternating magneto-optical effects are observed in the spectral vicinity of these points. [ABSTRACT FROM AUTHOR]

The paper presents the results of experimental and theoretical studies of nonlinear optical properties of LaFeO3 thin film, which is antiferromagnetic and centrosymmetric, the latter provides prohibition of second harmonic generation in electric-dipole approximation. Spectroscopic studies have shown the presence of the resonant frequency in the spectrum of optical second harmonic generation (SHG) at the pump photon energy 2ћω ≈ 2.85 eV. Comparison of SHG and absorption spectra at the second harmonic wavelength, the new characteristics have been identified, related to the presence of the electronic transition which results in the resonance spectral dependence. The models were suggested for the description of the polarization dependency for the two pump laser wavelengths (non-resonant 800 nm and resonant 860 nm), as well as for the calculation of the nonlinear susceptibility tensor components. The magnetically induced SHG was observed for the conditions of maximal suppression of crystallographic (electric dipole- or electric quadruple) contribution obtained by choice of appropriate polarization rules for the pump and second harmonic waves.

• Real-time magnetic Faraday rotation spectroscopy of Bi-YIG thin films is demonstrated. • Fiber-coupled spectrometer was used for the Faraday rotation spectroscopy. • The effect of annealing condition on the magnetic properties of Bi-YiG thin film was investigated. In this work, we have investigated the bismuth-substituted yttrium iron garnet (Bi-YIG) thin films prepared on glass substrate by modified metal-organic decomposition method. Real-time Faraday rotation spectrometer was used to characterize the magneto-optical properties of Bi-YIG films. The reliability of the measurement system and optimized analyzer setup was confirmed by comparing the Jones matrix calculations and measured results. The effect of annealing condition on the structural, magnetic and magneto-optical properties was investigated. A clear garnet-phase without secondary phase was observed for the Bi-YIG films annealed above 800 °C. Faraday rotation spectra of these films reveal the correlation between their crystallinity and magneto-optical properties. The highest Faraday rotation angle of −3.1 °/μm was achieved for 800 °C annealed sample. Simultaneous evaluation of real-time Faraday rotation spectra and the corresponding hysteresis loops can establish a path for the application of time-resolved magneto-optical spectroscopic analysis of magnetic thin films. [ABSTRACT FROM AUTHOR]

• Permalloy-based MPlC can be used as high sensitivity magnetic field sensor. • Change of MPlC composition allows one to vary modulating AC field. • MPlC-based sensor achieves sensitivity of 4.4 µOe in modulating AC field of 5.3 Oe. This work demonstrates a possibility of creating a magnetic field sensor based on magnetoplasmonic crystal with permalloy layer. Experimental results show that sensitivity of such sensors strongly correlates with the magnetic properties of magnetoplasmonic crystals and slightly depends on the value of transverse magneto-optical Kerr effect. The achieved sensitivity to DC magnetic field at local area of 1 mm2 was found to be 10−6 Oe in modulating field of 5 Oe. [ABSTRACT FROM AUTHOR]