Anisotropy of magnetooptical response of nanoperforated permalloy films

The azimuthal anisotropy of the linear and nonlinear magnetooptical Kerr effect has been studied for a structure that is an ordered array with 420-nm-diameter pores in a 30-nm-thick permalloy film on a silicon substrate. The azimuthal anisotropy of the magnetooptical Kerr effect and the coercive force, corresponding to 4 m symmetry of a planar nanopore array, has been established experimentally. The measurements are accompanied with the numerical calculation of the anisotropic magnetization distribution in the structure at different orientations of the applied magnetic field.     

Magnetooptical properties of Co-SiO<Subscript>2</Subscript> granular films

The structural, optical, and magnetooptical properties of Co-SiO₂ granular films are studied. It is found that the magnetooptical response is considerably enhanced in samples with a metal component concentration close to the percolation threshold. The Co nanogranules formed in the SiO₂ matrix exhibit ferromagnetic properties and are ordered into the fcc structure, which is confirmed by magnetooptical investigations. The magnetooptical properties of nanocomposites are simulated in the effective-medium approximation. It is shown that the singularities found in the magnetooptical spectra are related to the excitation of plasmon resonances in granular films.     

Investigation of small-scale stray magnetic fields by magnetooptical methods

Domain structures with in-plane magnetization are investigated in magnetically hard films. A magnetooptical setup designed for studying stray magnetic fields combines the advantages of the vibrating-sample magnetometer and the magnetooptical method of signal detection. The sensitivity of measurements of the stray field normal component is ～0.1 Oe. The criteria for choosing the optimal parameters of magnetooptical media for information readout are established.     

Magnetooptical Kerr effect in the near field of a nanowire supporting surface plasmons

In terms of Green’s functions, a theory is developed describing the resonant magnetooptical Kerr effect in light scattering by a linear probe that is parallel to the surface of a magnet and placed at a subwavelength distance from it. The probe is supposed to be a metal nanowire supporting long-lived surface plasmons and forming the near field of the “probe + image” complex. The resonant interaction between the probe and the sample is taken into account within a self-consistent approximation of multiple-scattering theory, and the magnetooptical interaction is included in the linear approximation in magnetization. The problem of scanning near-field magnetooptical microscopy with a linear probe is solved analytically in the case where the magnetization is parallel to both the magnet surface and the plane of incidence of light (longitudinal magnetooptical Kerr effect). The polarization, spectral, and angular characteristics of scattered light modulated by magnetization are discussed. It is shown that the magnetooptical modulation of the scattered light intensity is significantly enhanced when surface plasmons are resonantly excited in the nanowire.     

Magnetic and magnetooptical properties of ferromagnetic semiconductor GaN : Cr

Magnetic and magnetooptical properties of the Cr-doped GaN layers have been investigated in the temperature range 50–400 K. A high saturation magnetization of 25 G has been observed in the obtained material. Spectra of the magnetooptical transversal Kerr effect have revealed strong magnetic response in the energy range less than 3.0 eV due to the appearance of new spin-polarization states in the band gap of GaN upon Cr doping.     

Features of two-photon resonances of nonlinear magnetooptical rotation of the plane of polarization for the initial population of fine-structure levels in alkali atoms

The features of nonlinear magnetooptical effects of fine-structure levels of an alkali atom, including effects in strong magnetic fields, as well as under conditions of two-photon resonance, are considered. The spectra of magnetooptical rotation and of magnetic circular dichroism have been obtained for the first time for the nontrivial initial population of magnetic sublevels of excited electronic states of an alkali atom, as well as under conditions of two-photon resonance. The decrease in the amplitude of resonances of initially populated fine-structure levels is explained by population transfer, taking place in strong fields. This transfer affects the rotation of the plane of polarization. The lower the initial population, the more pronounced the population transfer. Numerical experiments have shown that analysis of the resonance shapes in the spectra of magnetooptical rotation can yield information on the initial population of magnetic sublevels of excited electronic states of atoms.     

Doppler cooling and trapping on forbidden transitions

Ultracold atoms at temperatures close to the recoil limit have been achieved by extending Doppler cooling to forbidden transitions. A cloud of (40)Ca atoms has been cooled and trapped to a temperature as low as 6 microK by operating a magnetooptical trap on the spin-forbidden intercombination transition. Quenching the long-lived excited state with an additional laser enhanced the scattering rate by a factor of 15, while a high selectivity in velocity was preserved. With this method, more than 10% of precooled atoms from a standard magnetooptical trap have been transferred to the ultracold trap. Monte Carlo simulations of the cooling process are in good agreement with the experiments.     

榕树型互连网络及光学实现

讨论了一种用扭曲向列相液晶器件和偏振分光棱镜实现光学榕树上互连网络的结构，这种结构具有直线式传输、无错位、无缩放，并能够实现模块化和集成化的优点。     

The possibility of measuring linear and quadratic magnetooptical effects in magnetic field under conditions of magnetomechanical resonance

We have considered the possibility of measuring the linear and quadratic (in magnetic field) magnetooptical effects in magnetooptical crystals that are simultaneously exposed to a constant (polarizing) magnetic field and to an alternating magnetic field under conditions of magnetomechanical resonance. The use of a Mueller polarimeter in combination with spectral analysis of the intensity of the light wave at the output of the polarimeter makes it possible to selectively determine elements of the Mueller matrix and minimize the amount of measurements. We have shown that there is a possibility of solving the inverse problem on finding two components of the alternating magnetic field in which a magnetooptical crystal is placed.     

双光束磁光存贮中信号读出的偏振态分析

利用琼斯矩阵分析了双光束磁光存贮中信号读出系统偏振态的传输情况，推导了读出信号的表达式，分析了偏振分束镜与光盘盘基的相位延迟对读出信号的影响。     

Rapid determination of the gas temperature in magnetooptical traps

We have considered a simple method for estimating the gas temperature in a magnetooptical trap. In this method, only one of three laser beams in the magnetooptical trap is shut down. Then, the light scattered by the atoms of the remaining beams makes it possible to observe the spread of the atoms in real time without using additional lasers. An analysis of the measuring data has convincingly proved their conformity with theoretical estimates. This method can be useful for the approximate express analysis of the magnetooptical trap performance.     

Reflection and transmission of light by a ferromagnetic structure with a noncollinear orientation of the magnetization of layers

The transmission and reflection of light by a ferromagnetic structure with a noncollinear orientation of the magnetization vectors of layers lying in the plane of the film is considered. The characteristic matrix of the structure that relates the wave amplitudes at the entrance to the system and at the exit from it and that determines the magnetooptical properties of the structure is calculated. The magnetooptical characteristics of this structure are shown to significantly depend on the angle between the magnetization vectors of layers and on the number of layers. Both the magnitude and the character of these dependences are analyzed in relation to the angle of incidence and to the polarization of the incident wave. Such an analysis makes it possible to optimize the magnetooptical properties of this structure.     

Magnetooptic effects in antiferromagnetic chromium

Transverse and polar Kerr effects and quadratic magnetooptical effect in reflected light have been discovered and studied in antiferromagnetic chromium. Measurements have been performed in IR, visible, and UV ranges of spectrum in a magnetic field H = 10 kOe. The frequency dispersion of the off-diagonal component of the dielectric constant tensor $\hat \varepsilon $ of chromium has been determined for the first time. An analysis of the magnetooptical data obtained is carried out on the basis of available data on the electronic structure of chromium.     

Magnetic and magnetooptical properties of multilayer ferromagnet-semiconductor nanostructures

The magnetic and magnetooptical properties of spin-tunneling multilayer permalloy-silicon carbide nanoheterostructures deposited by rf sputtering have been studied. Magnetometric and magnetooptical methods are used to show that the magnetic-semiconducting nanostructures have a complex magnetic structure and to track the evolution of the magnetic properties of these structures as functions of the magnetizing field and the thickness and sequence order of ferromagnetic and semiconducting layers in them. The induction response and the field and orientation dependences of the transversal Kerr effect are found to have anomalies. The experimental results are interpreted under the assumption that there is exchange interaction between the ferromagnetic and semiconducting layers through a thin magnetically ordered transition layer formed inside the interface.     

Analysis of Different Contributions into the Magnetooptical Signal of Magnetophotonic Crystal Type Three-Dimensional Structures

Interference of effects of different levels and magnitudes in producing a net magnetooptical response was considered for the first time in structures similar to magnetophotonic crystals at different wavelengths of the incident irradiation in regions far from plasmon resonances. Contributions of interference and diffraction phenomena in maxima of different orders in three-dimensional systems of the magnetophotonic crystal type were studied. Use of the integral response in the analysis of the magnetooptical effects was shown to lead to disappearing of the interference phenomena. The zero-order diffraction maximum reflects adequately the magnetic component of the magnetooptical response. Numerical estimates of the observed diffraction and interference effects are reported.     

利用磁光效应测电流

本文介绍了一种磁光电流传感器的测试原理和实验方法，并对ＫＣ１饱和溶液和ＹＩＧ固体薄膜的磁光特性进行了分析。     

Theory of scanning near-field magnetooptical microscopy

An analytical theory of scanning near-field magnetooptical microscopy is developed. The theory is based on the elastic scattering of light by small, resonantly polarizable particles, which are used to scan the plane surface of a nonuniformly magnetized medium. The effective polarizability of the particles is calculated with the effect of dynamic “image forces” taken into account in all orders of perturbation theory with respect to the interaction of the particle with a demagnetized ferromagnet, and the magnetooptical perturbation is calculated to first order in the magnetization. The major contributions to the magnetooptical light scattering for a ferromagnetic structure magnetized perpendicular to the surface are found, including a quasistatic approximation for the near-field particle-magnet interaction. The optical size resolution of a magnetic (dielectric) inhomogeneity is estimated. Zh. Tekh. Fiz. 68, 86–91 (July 1998)     

Magnetooptical properties of YIG measured on a continuously working spectrometer

A spectrometer is described which allows continuous recording of four transmission magnetooptical effects: Magnetic linear and circular birefringence and magnetic linear and circular dichroism. The set-up has been used to measure magnetooptical spectra of Yttrium Iron Garnet (YIG) in the visible spectra range. Two of the spectra are reported here, namely, the magnetic linear dichroism and the magnetic linear birefringence (Cotton Mouton effect).     

Enhancement of the Kerr effect in magnetooptical DyFeCo/GeO carriers

The optimum parameters of a dielectric layer near the substrate in the interference multilayer structure are calculated. The calculations showed that this layer should have the index of refraction n∼3. The results are presented of measuring the Kerr angle of magnetooptical rotation in the multilayer structure, in which GeO films were used as dielectric layers for the first time. The maximum Kerr angle of rotation and magnetooptical quality observed in this system were 0.75° and 0.34°, respectively. These values exceed those inherent in the known information carriers, which demonstrates the advantage of this structure for use in magnetooptical discs.     

Magnetooptische und optische Eigenschaften von ferromagnetischen Schichten im Ultraroten

The rotation of the plane of polarisation and the ellipticity of the reflected light at both sides and the transmitted light through magnetically saturated evaporated layers (30 mμ) of iron, cobalt and nickel are measured in the near I.R. and the visible spectrum (2·5 to 0·43 μ). The four measured magnetooptical angles are dependent one another according to the theory ofVoigt. They are found independent however each other. That can be explaned only by a magnetooptical term in the second equation of Maxwell too, if the layers are homogenous. This term is calculated and gives rise to a considerable portion of the magnetooptical effects. The transmitted light gains a rotation and ellipticity not only in the interior of the metal but also on the surfaces. This surface-change surpasses that in the interior in the I.R. region. It can be determined by extrapolating on the thickness zero or by calculating out of the measured Kerr-effect. Both methods agree well. This is a convincing prove that non-magnetical surface-layers are there not existing. The magnetooptical rotation of Nickel has a sharp peak at 1 μ, the other magnetooptical constants, include the calculated magnetical terms show a more monotonous course with the wavelenght, also for the other metals. The optical constants are determined by measurements of intensity of the reflected light on both sides of the layer and of the transmitted light.