Ultra-thin magnetic dielectric films are of prime importance due to their applications for nanophotonics and spintronics. Here, we propose an efficient method for the magneto-optical investigation of ultra-thin magnetic films which allows one to access their state of magnetization and magneto-optical properties. It is based on the surface-plasmon-polariton-assisted transverse magneto-optical Kerr effect (TMOKE). In our experiments, sub-100 nm-thick bismuth-substituted lutetium iron-garnet films covered with a plasmonic gold grating have been analyzed. The excitation of surface plasmon-polaritons provides resonance enhancement of TMOKE up to 0.04 and makes it easily detectable in the experiment. For films thicker than 40 nm, the TMOKE marginally depends on the film thickness. A further decrease in the film thickness diminishes TMOKE since for such thicknesses the surface plasmon-polariton field partly penetrates inside the non-magnetic substrate. Nevertheless, the TMOKE remains measurable even for few-nm-thick films, which makes this technique unique for the magneto-optical study of ultra-thin films. Particularly, the proposed method reveals that the off-diagonal components of the magnetic film permittivity tensor grow slightly with the reduction of the film thickness.

In previous decades, significant efforts have been devoted to increasing the magneto-optical efficiency of iron garnet materials for the miniaturization of nonreciprocal devices such as isolators and circulators. Elemental substitutions, or proper nanostructuring to benefit from optical resonances, have been pursued. However, all these approaches still require film thicknesses of at least several tens of microns to deliver useful device applications, and suffer from narrow bandwidths in the case of optical resonance effects. This paper reports on a newly discovered enhancement of the Faraday effect observed experimentally in nanoscale bismuth-substituted iron garnet films. It is shown here that this enhancement is not due to elemental substitution or compositional variations, nor is it due to photon trapping or resonance effects. Comprehensive experimental and theoretical analysis of the Faraday rotation reveals a dramatic sevenfold amplification in the magneto-optic gyrotropy within only 2 nm of the air–surface interface, corresponding to just a couple of atomic monolayers as a result of symmetry breaking at the air–film interface. This finding opens up an avenue to the application of monolayer magnetic garnets for the control of light.

The mid-infrared spectrum can be recorded from almost any material, making mid-infrared spectroscopy an extremely important and widely used sample characterization and analysis technique. However, sensitive photoconductive detectors operate primarily in the near-infrared (NIR), but not in the mid-infrared, making the NIR more favorable for accurate spectral analysis. Although the absorption cross section of vibrational modes in the NIR is orders of magnitude smaller compared to the fundamental vibrations in the mid-infrared, different concepts have been proposed to increase the detectability of weak molecular transitions overtones. Yet, the contribution of magnetophotonic structures in the NIR absorption effect has never been explored so far. Here we propose high-Q magnetophotonic structures for a supersensitive detection of weak absorption resonances in the NIR. We analyze the contributions of both magnetic and nonmagnetic photonic crystal configurations to the detection of weak molecular transitions overtones. Our results constitute an important step towards the development of highly sensitive spectroscopic tools based on high-Q magnetophotonic sensors.

We propose a novel method to enhance the transverse magneto-optical Kerr effect (TMOKE) in the magneto-plasmonic (MP) nanostructures by means of the active dielectric layer. We report the theoretical analysis of the MP structure with a ferromagnetic dielectric doped with rear-earth ions (${\mathrm{Nd}}^{3+}$) as the example of a gain layer. The enhancement takes place near the surface plasmon polariton (SPP) resonances of the nanostructures. The stimulated emission of the dopants in the field of the SPP wave partially compensates its losses. It is shown that due to a decrease of SPP damping, a $Q$-factor of the MP resonance increases and the TMOKE is increased in comparison with the passive nanostructure.

The homogeneous nucleation of bismuth supersaturated vapor is studied in a laminar flow quartz tube nucleation chamber. The concentration, size, and morphology of outcoming aerosol particles are analyzed by a transmission electron microscope (TEM) and an automatic diffusion battery (ADB). The wall deposit morphology is studied by scanning electron microscopy. The rate of wall deposition is measured by the light absorption technique and direct weighting of the wall deposits. The confines of the nucleation region are determined in the “supersaturation cut-off” measurements inserting a metal grid into the nucleation zone and monitoring the outlet aerosol concentration response. Using the above experimental techniques, the nucleation rate, supersaturation, and nucleation temperature are measured. The surface tension of the critical nucleus and the radius of the surface of tension are determined from the measured nucleation parameters. To this aim an analytical formula for the nucleation rate is used, derived from author's previous papers based on the Gibbs formula for the work of formation of critical nucleus and the translation-rotation correction. A more accurate approach is also applied to determine the surface tension of critical drop from the experimentally measured bismuth mass flow, temperature profiles, ADB, and TEM data solving an inverse problem by numerical simulation. The simulation of the vapor to particles conversion is carried out in the framework of the explicit finite difference scheme accounting the nucleation, vapor to particles and vapor to wall deposition, and particle to wall deposition, coagulation. The nucleation rate is determined from simulations to be in the range of 10⁹–10¹¹ cm⁻³ s⁻¹ for the supersaturation of Bi₂ dimers being 10¹⁷–10⁷ and the nucleation temperature 330–570 K, respectively. The surface tension σ_S of the bismuth critical nucleus is found to be in the range of 455–487 mN/m for the radius of the surface of tension from 0.36 to 0.48 nm. The function σ_S changes weakly with the radius of critical nucleus. The value of σ_S is from 14% to 24% higher than the surface tension of a flat surface.

As magnetized media by their nature have broken time reciprocity, the spatial symmetry of a material is also crucial and it imposes some restrictions on observed optical phenomena. Thus, for the normal incidence of light the spatial inversion symmetry makes transmitted and reflected light insensitive to the direction of the in-plane magnetization of the sample. To avoid this limitation, we propose here an approach based on a magnetoplasmonic structure with broken spatial symmetry. Combination of the specially designed spatial asymmetry with magnetism in the presence of optical losses provides a different effect, the transverse magnetophotonic transmittance effect, notable magnetooptical modulation of the optical transmittance at normal incidence enhanced by surface plasmon excitation. As the phenomenon is sensitive to asymmetry, it can serve as a powerful tool to study spin waves and currents in magnonic and optospintronic devices. The approach to marry the concepts of magnetoplasmonics and a lack of spatial symmetry is promising for the design of nanophotonics devices with outstanding properties.