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The features of magnetization of rare-earth multiferroic PrFe3(BO3)4 with the singlet ground state have been investigated theoretically. The magnetic anisotropy of the crystal has been studied. The temperature dependences of anisotropy constants have been calculated. The phase H-T diagram has been constructed. The dependences of the behavior of magnetization vectors of magnetic sublattices on the external magnetic field have been obtained. The magnetoelectric effect has been investigated, and the dependences of polarization on the temperature and field have been found for its various orientations. The theoretical data have been compared with the experimental data and their good agreement has been established. 相似文献
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E. M. Baitinger E. A. Belenkov M. M. Brzhezinskaya V. A. Greshnyakov 《Physics of the Solid State》2012,54(8):1715-1722
The experimental results of a comprehensive investigation of the structure of detonation synthesis nanodiamonds by electron microscopy methods have been presented. The morphology of diamond nanoparticles has been investigated and the microdiffraction patterns have been analyzed. The method of characteristic fast electron energy loss spectroscopy in transmission electron microscopy has been used. The local density of structural components of a nanodiamond (diamond core and fullerene-like shell) has been obtained. The shape of the shell surrounding the nanocrystal has been determined using model calculations. A hypothesis explaining the charging of the nanodiamond surface has been proposed. 相似文献
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北京正负电子对撞机二期(BEPCⅡ),国产500 MHz超导腔经过紧张的安装调试于2017年10月正式投入带束流运行。首先对此国产超导腔两次降温调试的相关参数进行了监测和对比分析;其次研究了通过高功率老练的方法改善超导腔的品质因数,并实时监测超导腔老练过程中的辐射剂量;最后对超导腔的带束流运行情况进行了介绍分析。结果表明:BEPCⅡ国产500 MHz超导腔虽然放置了6年,但是状态良好,通过高功率老练能够降低超导腔的辐射剂量,改善其性能,完全满足束流运行要求。 相似文献
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A. V. Rogachev A. I. Kuklin A. Yu. Cherny A. N. Ozerin A. M. Muzafarov E. A. Tatarinova V. I. Gordeliy 《Physics of the Solid State》2010,52(5):1045-1049
The structure of organosilicon dendrimers of the ninth generation with the four-functional core and butyl terminal groups
has been studied by small-angle neutron scattering. It has been demonstrated that the dendrimers are monodisperse objects
with an anisometric shape. The partial volume and the average scattering density have been determined using the contrast variation
technique. It has been shown that the dendrimers under study are identical in overall sizes and scattering density distribution.
It has been revealed that 20% of the overall volume of the dendrimer is accessible for the penetration of the solvent. The
distribution of the scattering length density in the dendrimers has been simulated and reconstructed using the Monte Carlo
method, and a change in the excluded volume for different contrasts has been revealed. The specific features of the spatial
structure of organosilicon dendrimers of higher generations have been discussed. 相似文献
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《Waves in Random and Complex Media》2013,23(4):506-535
The couple stress theory developed by Eringen comprises granular materials as also composite fibrous materials. As such, micropolar materials present an inclusive model of composite materials. This article endeavors to study aspects of wave propagation in a random weakly thermal micropolar elastic medium. The smooth perturbation technique has been employed. The classical thermoelasticity has been used. Six different types of waves have been observed to propagate in the random interacting medium. Dispersion equations have been derived. The effects due to random variations of micropolar elastic and thermal parameters have been observed. Change of phase speed occurs on account of randomness. Attenuation coefficients for high-frequency waves have been computed. Second moment properties have been discussed with application to wave propagation in the random micropolar elastic medium. 36 + 1 components of the associated Green’s tensor have been computed. Integrals involving correlation functions have been transformed to radial forms. A special type of correlation function has been used to approximately measure effects of random variations of parameters. 相似文献
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The effect of angular momentum on an excited paired nucleus has been studied. The BCS Hamiltonian, modified to include the z-projection of angular momentum has been diagonalized and expressed in terms of the quasiparticle occupation numbers. The grand partition function and all the relevant thermodynamical functions as well as the level-density expression have been derived for the general case of an arbitrary set of single-particle levels. Furthermore, the formalism has been applied to the uniform model and, whenever possible, analytical expressions have been derived. In particular the zero-temperature angular momentum dependence of the gap parameter, the critical angular momentum as well as the yrast line have been calculated. The critical temperature as a function of angular momentum, which defines the phase transition between paired and unpaired systems, has been calculated. A new effect called the thermally assisted pairing correlation, involving an increase of pairing with increasing temperature has been predicted. The completeness of the formalism as applied to spherical or deformed nuclei has been discussed. 相似文献
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K. V. Karelsky A. S. Petrosyan S. V. Tarasevich 《Journal of Experimental and Theoretical Physics》2011,113(3):530-542
The system of the magnetohydrodynamic equations for a heavy fluid has been analyzed in the shallow water approximation. All
discontinuous self-similar solutions and all continuous centered self-similar solutions have been found. It has been shown
that magnetogravity compression waves are broken with the formation of a magnetogravity shock wave. The initial decay discontinuity
problem for the magnetohydrodynamic equations has been solved in the explicit form in the shallow water approximation. The
existence of five different configurations implementing the solution of the decay of an arbitrary discontinuity has been demonstrated.
The conditions necessary and sufficient for the implementation of each configuration have been found. 相似文献
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The 94Mo(n, n′γ) reaction has been studied in the neutron energy range 1.5–4.0 MeV. Neutron inelastic scattering cross sections for levels up to an excitation energy of 2.6 MeV have been measured from 1.5 to 3.0 MeV. The results have been analyzed with the optical-statistical and coupled-channels theories. The 1.74 MeV level has been observed and has been assigned to be 0+. The branching ratios for the γ-rays deexciting the levels below the 3.5 MeV excitation have also been obtained. 相似文献
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S. A. Al’ Rifai B. M. Darinskii A. P. Lazarev A. S. Sigov 《Physics of the Solid State》2012,54(5):980-983
The conditions for the phase transition to the ferroelectromagnetic phase in ferroelectric-ferromagnetic films through the mechanism of the loss of stability of the initial homogeneous state have been considered. The geometry of the domain structure and the temperature of the transition to the inhomogeneous state have been determined. The condition for the phase transition to the ferroelectromagnetic phase has been established and determined by the relationship between the temperature-dependent coefficients of the expansion of the thermodynamic potential into a series in terms of the polarization and magnetization vector components. The influence of free charge carriers on the geometry of the domain structure and the transition temperature has been studied. The possible existence of a single-domain state has been discussed. The permittivity of a multidomain sample has been determined. The feasibility of exploiting the studied material for nondestructive recording and reading of information has been noted. 相似文献
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Formulas for calculating the intensity of intrabeam scattering of electrons in the Born approximation for the one- and two-dimensional collision models have been obtained for the nonrelativistic and relativistic cases. The Baier-Katkov-Strakhovenko two-dimensional relativistic model with Coulomb corrections has been analyzed. Formulas in the ultrarelativistic limit have been obtained using this model. Different models have been compared. The intensities of Touschek electrons and the polarization contribution have been calculated under the conditions of the detection of scattered particles at the VEPP-4M storage ring. The calculations have been compared to experimental data. 相似文献
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S. V. Sazonov 《JETP Letters》2012,96(4):263-274
Various methods to increase the efficiency of the generation of broadband terahertz radiation based on optical rectification have been analyzed. The solutions of self-consistent optical terahertz equations have been studied using the inclined front technique. The effect of symmetric and asymmetric resonant impurity centers incorporated into a crystal has been examined. Transient and asymptotic stages of generation have been considered. Attention has been focused on the evolution of the spectra of both generated terahertz and input optic signals. One- and two-frequency generation modes have been discussed. Acoustic analogs that would provide the possibility of the generation of the gigahertz acoustic supercontinuum using subterahertz elastic signals in a solid have been analyzed. The main similarities and differences between terahertz optics and subterahertz acoustics have been revealed. 相似文献
13.
The mechanism and stochastic properties of the homogeneous nucleation of dislocations have been studied. An approach has been
proposed for determining the nucleation rate based on consideration of the lifetimes of a metastable state. Primary data have
been obtained using the molecular dynamics method. The dependences of the nucleation rate on the shear stresses have been
determined for several temperatures. An approximation of the obtained results in terms of the Arrhenius equation has been
proposed. The regions of shear stresses and temperatures in which the mechanism of homogeneous dislocation nucleation can
be realized have been estimated. 相似文献
14.
基于非接触式光学测振和有限元反演对黏弹材料复模量的测量进行了理论和实验研究。针对反演精度受测点选择影响显著的问题进行了误差分析,推导了灵敏度矩阵的计算公式;得到了反演误差的计算方法;找出了影响反演精度的主要误差来源;通过测点优化,提高了泊松比测试精度。利用温频等效原理,在常压、变温条件下对橡胶样品进行了温频等效测量,实验研究表明,该系统可以以较少的温度台阶获得材料主曲线,反演结果与动态机械分析仪(DMA)测试结果误差在10%以内,进一步印证了反演系统的有效性。 相似文献
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The dispersion and energy characteristics of surface polaritons at a high-temperature supercon-ductor-insulator interface
have been studied taking into account the dissipation in both media. The dispersions have been found and the criteria for
the existence of surface waves have been formulated for temperatures below the phase transition point. The frequency dependences
of the depth of penetration of surface polaritons into each medium and their mean free paths have been determined. The characteristic
frequencies near which the wave parameters of surface polaritons undergo substantial changes have been revealed. 相似文献
17.
A. Yu. Ozerin 《JETP Letters》2014,98(12):839-842
The dynamic conductivity of graphene in a magnetic field under the conditions of cyclotron resonance has been calculated. The effect of the temperature on cyclotron resonance has been analyzed. So-called multiple resonances have been considered. A dimensionless quantity determining the width and amplitude of the cyclotron peak in the conductivity has been found. Coulomb corrections to the electronic spectrum have been discussed. 相似文献
18.
Thanassis Speliotis Dimitris Niarchos Patrick Meneroud G. Magnac Franck Claeyssen John Pepin Claude Fermon M. Pannetier N. Biziere 《Journal of magnetism and magnetic materials》2007
The feasibility to develop mini- and micro-magnetic electro-mechanical systems (MEMS) has been evaluated by prototyping of a single-phase stepper motor. The main targeted application of such device is the watch industry needing micro-motors in huge quantities at low cost. The motor part that required the greatest efforts has been the magnet, which cannot yet be found in film layer. The screen-printing technology has been used for the production of NdFeB-based magnets whose properties have been characterised. The thick film magnets have been integrated in the stepper motor specially designed for this purpose. The whole motor has been characterised and conclusions are drawn on the possibility of producing thick film magnets for magnetic MEMS. 相似文献
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Very high purity single crystals have been successfully grown by the method of vertical zone refining. The problem of excessive evaporation of the material, confronted by the earlier workers, has been successfully overcome. The purity of the crystals has been tested by D. C. conductivity measurements and further confirmed by U. V. spectroscopy. X-ray diffraction has been employed for the characterization of the crystals. The crystals have been found to crystallize exclusively in 6R polytypic modifications, without any arcing and streaking on their X-ray photographs. The results have been discussed in relation to the effect of impurities on polytype formation. 相似文献
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The magnetic structure of the compensated ferromagnet-multiferroic interface has been considered. The law governing the decrease of distortions of magnetic order parameters with increasing distance from the interface has been found. An expression for the energy of interlayer interaction of magnetic order parameters has been derived, and it has been shown that its magnitude is determined by the exchange interaction. The condition for magnetization switching of the ferromagnetic layer by an electric field applied to the multiferroic layer has been formulated. It has been demonstrated that the magnetoelectric effect and weak ferromagnetism are not prerequisites to the development of electric field-switchable magnetoresistive memory. 相似文献