动态磁滞回线实验的不确定度评定

本文主要讨论动态磁滞回线实验结果的不确定度评定。通过简要分析,提出改进实验装置以及提高测量精度的方法。在计算过程中,借助MATLAB使计算大大简化。     

Mathematic软件在铁磁材料磁滞回线中的应用

根据铁磁材料磁滞回线的实验原理,利用绘图软件Mathematic绘制出样品的磁化曲线和磁滞回线,对实验数据进行多项式函数拟合,计算出其磁滞损耗。     

Magnetooptical effects in the metal-dielectric gratings

A significant enhancement of the magnetooptical Faraday effect in the bilayer heterostructure of a thin metallic layer pierced by an array of parallel subwavelength slits and a uniform dielectric layer magnetized perpendicular to its plane, is reported. Calculations, based on the rigorous coupled-wave analysis of Maxwell’s equations, demonstrate that in such structures the Faraday effect spectrum has several resonance peaks in the near-infrared range, some of them coinciding with transmittance peaks, providing simultaneous large Faraday rotation enhanced by an order and high transmittance of about 35%. It is shown that the excitation of the quasi-guided TM- and TE-modes in the dielectric layer mostly governs the enhancement of the Faraday rotation.     

Susceptibility and Inverted Hysteresis Loop of Prussian Blue Analogs with Orthorhombic Structure

The magnetic susceptibility of ternary metal Prussian blue analogues with orthorhombic structure is studied using Ising model. Within the frame work of effective-field theory with correlations, the roles of the mole fraction y, uniaxial magnetic anisotropy, transverse and longitudinal magnetic field are discussed in details. The temperature dependence of the magnetic susceptibility is also investigated. The interesting phenomenon of the inverted magnetic hysteresis loop has been found. The results can help to understand the experimental work of the molecule-based ferri-ferrimagnet.     

Susceptibility and Inverted Hysteresis Loop of Prussian Blue Analogs with Orthorhombic Structure

The magnetic susceptibility of ternary metal Prussian blue analogues with orthorhombic structure is studied using Ising model. Within the frame work of effective-field theory with correlations, the roles of the mole fraction y, uniaxial magnetic anisotropy, transverse and longitudinal magnetic field are discussed in details. The temperature dependence of the magnetic susceptibility is also investigated. The interesting phenomenon of the inverted magnetic hysteresis loop has been found. The results can help to understand the experimental work of the molecule-based ferriferrimagnet.     

示波器观测动态磁滞回线实验中曲线描绘浅析

给出了示波器观测铁磁材料物质磁滞回线的基本原理,针对实验中常见的错误,介绍了如何选取合理的数据并快速描绘磁滞回线的技巧。     

基于Matllab的约束最小二乘法拟合磁滞回线

由实验测得的磁滞回线数据的是一系列离散、带噪声的值。通过约束最小二乘方法对曲线进行分段拟合,使曲线的畸变程度得到了改善,准确地表达磁滞回线的特性,为磁材料的定量分析述提供了基础。     

Magnetooptical absorption of a molecular crystal in the exciton frequency range

Nonlinear absorption of a molecular crystal in an external magnetic field is considered. The exciton absorption shape functions under polarized laser radiation and a weak magnetic field, as well as the mechanisms responsible for the formation of a hysteresis loop in the dependence of the output light intensity on the applied magnetic field, were studied for the particular case of benzene. It was established that, for the magnetooptical response of the molecular crystal under study, the formation of bistable loops is inverse in character, which makes it possible to monitor and control the behavior of bistable elements in optical logics systems with an external magnetic field at a fixed illumination frequency.     

Magnetooptical effects in ferromagnetic metals at low temperatures

Zeroth-order and first-order Boltzmann kinetic equations are found for the frequency-dependent transverse-conductivity tensor for inelastic scattering of electrons, with an account of thermal oscillations of the scattering centers. At low temperatures this tensor, which is linear in the spin-orbit interaction, depends exponentially on the temperature. A relation is found between the magnetooptical effects in ferromagnetic metals and the topology of the Fermi surfaces; from this relation, qualitative conclusions can be drawn regarding the effect of this topology on the magnetooptical effects and regarding the sign of the anomalous magnetooptical parameter (which depends on whether hole or electronic conductivity predominates).Translated from Izvestiya VUZ. Fizika, No. 4, pp. 86–90, April, 1970.     

Hysteresis in the Lorenz equations

The phenomenon of hysteresis, associated with multiple stable solution behaviours, has been predicted and observed in the Lorenz equations when r and σ are large.     

Magnetooptical bistability of a layered semiconductor in the region of exciton absorption

The effect of weak external magnetic fields on the conditions for implementing optical bistability in the region of exciton absorption of layered semiconductors has been theoretically investigated. By the example of the 2H polytype of lead diiodide, it is shown that, changing the strength of an external magnetic field, one can form conditions for implementing bistability and effectively control the position and sizes of the hysteresis loop of exciton absorption.     

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.     

Magnetooptical studies of aggregates of nanoparticles in colloidal solutions of magnetite

The birefringence in a colloidal solution of nanosized magnetite particles in kerosene exposed to constant, alternating, and pulsed magnetic fields is studied. Data on the birefringence kinetics in nonstationary magnetic fields is used to determine the hydrodynamic radius of particle aggregates in solutions. The permanent dipole moment of aggregates and the anisotropy of the magnetic susceptibility are calculated based on the data of magnetooptical experiments. It is shown that the induced dipole moment plays a significant role in an orientation of aggregates of magnetic nanoparticles under the effect of a field.     

Magnetooptical method of measuring the characteristics of the reservoir of spin-spin interactions in paramagnets

Based on the phenomenon of coherent spin Raman scattering a magnetooptical method of measuring the characteristics of the reservoir of electronic spin-spin interactions in paramagnets was implemented. A formula relating the intensity of the inelastically scattered light to the temperature of the spin-spin reservoirs under conditions of saturation of the EPR of paramagnetic ions has been derived. For the Ce³⁺ ions in the (Ce_xLa_1−x)₂Mg₃(NO₃)₁₂·24H₂O crystal values of the time of spin-lattice relaxation of the spin-spin reservoir and the local magnetic field have been measured, and a relation between the spin-spin reservoir temperature and the external magnetic field strength under conditions of stationary saturation of the EPR of the Ce³⁺ ions has been obtained. V. I. Ul’yanov-Lenin Kazan State University,18, Lenin St., Kazan, 420008, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 76–81, January–February, 1997.     

Magnetooptical force in the resonance field formed by elliptically polarized light waves

The screening of the Coulomb interaction is studied with regard to Friedel oscillations in multicomponent electron plasma structure. A double quantum well (QW) and a superlattice are considered. The groundstate energy of a donor (exciton) in a double quantum well is calculated by a variational method as a function of the population of subbands.     

Hysteresis in the presence of electron-cyclotron resonance

A method of determining the nonlinear interaction of microwaves with a magnetoactive lowpressure plasma is presented. It is shown by solving simultaneously the problems of the propagation of electromagnetic waves, the balance of charged particles, and the energy balance that near a critical value of the constant magnetic induction the character of the interaction of the wave and the plasma changes substantially: For magnetic fields above the critical field a much stronger interaction is observed, for which the penetration depth of the incident wave into the plasma increases. An investigation of the strong interaction regime showed the existence of hysteresis, which is accompanied by an abrupt transition from one standing-wave mode in plasma to another. It is shown that virtually complete absorption of the wave is possible. Zh. Tekh. Fiz. 69, 31–37 (December 1999)     

Magnetooptical images of inhomogeneous magnetic fields in metallic films with in-plane anisotropy

The magnetooptical (MO) images of the inhomogeneous field created by permanent magnets in magnetic metallic films with in-plane anisotropy are experimentally studied. The MO images recorded using the longitudinal Kerr effect are the superposition of two pictures, namely, a polar-sensitivity MO image and a longitudinal-sensitivity MO image. An analysis of these images after separation shows that the polar-sensitivity MO image reflects the distribution of the inhomogeneous field component that is normal to the surface of an indicator film in an analog manner. The longitudinal-sensitivity MO image reflects the angular distribution of the in-plane component of a stray field in an analog manner. The coincidence of the experimental and corresponding simulated MO images makes it possible to interpret the experimental images. In particular, it is shown that the specific features detected in the topological characteristics of the inhomogeneous field correspond to experimental singular points. Hidden magnetic images (magnetic bar codes) are shown to be visualized with metallic CoFe films. As an example, the stray field of a magnetic system made of cylindrical magnets is mapped.     

Efficiency of Magnetooptical Conversion of Magnetic Fluxes Produced by the High-Temperature Superconductor Matrix

The possibility for using the ferrite-garnet magnetooptical films with a band domain structure has been considered with the aim of visualization of the spatial distribution of a magnetic flux near sensitive elements of a high-temperature superconductor matrix. The methods that enhance the efficiency of magnetooptical conversion have been suggested.