共查询到20条相似文献,搜索用时 31 毫秒
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Magnetic hysteresis properties of antiferromagnetically exchange-coupled bilayer structures, in which the two magnetic layers have different magnetic parameters and thicknesses, are studied within the framework of the Stoner-Wohlfarth model. Analytical expressions for the switching fields corresponding to the linear magnetic states are obtained. By adjusting the magnetic parameters or thicknesses of layers, nine different types of easy-axis hysteresis loops may exist. The phase diagram of easy-axis hysteresis loops is mapped in the k1 and k2 plane, where k1 and k2 are the ratios of magnetic anisotropy to the interlayer exchange coupling of the two magnetic layers, respectively. 相似文献
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Z. Q. Chen L. P. Guo Y. Chen X. L. Li G. Q. Liu Y. H. Ji Z. S. Wang 《International Journal of Theoretical Physics》2010,49(1):18-24
A different strategy is proposed to control decoherence from fluctuating magnetic field by adjusting external controllable
parameters. The results show that the output states in terms of the fidelity are pure states, which correspond to the state
vectors that are given by a renormalized Hamiltonian. Thus, the output states may perfectly preserve memory of initial single-qubit
states at some critical magnetic field parameters. 相似文献
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The generation and evolution of magnetic inhomogeneities of the stationary breather type, which appear in a flat layer with the magnetic anisotropy and exchange interaction parameters that are different from those in the bulk of an infinite ferromagnet after transmission through a 180° domain wall, have been investigated theoretically. The dependences of the amplitude and frequency of vibrations on the parameters of the defect have been constructed for the revealed magnetic inhomogeneities, and the ranges of the parameters determining the possibility of their existence have been found. 相似文献
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A spin-1 transverse Ising model with longitudinal crystal field in a longitudinal magnetic field is examined by introducing an effective field approximation (IEFT) which includes the correlations between different spins that emerge when expanding the identities. The effects of the crystal field as well as the transverse and longitudinal magnetic fields on the thermal and magnetic properties of the spin system are discussed in detail. The order parameters, Helmholtz free energy, entropy and specific heat curves are calculated numerically as functions of the temperature and Hamiltonian parameters. A number of interesting phenomena such as reentrant phenomena originating from the temperature, crystal field, transverse and longitudinal magnetic fields have been found. 相似文献
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将薄的磁谐振介质板等效为面磁流, 利用周期性边界条件, 给出了面磁流的指数形式. 通过计算无穷个面磁流在不同空间位置上产生的总电场和总磁场, 推导出了周期性磁谐振人工材料的色散关系和布洛赫阻抗, 进而获取了布洛赫本构参数的理论计算公式. 由于考虑了磁谐振人工材料中的电反谐振对布洛赫介电常数和磁导率的影响, 所以基于仿真实验的布洛赫本构参数的提取值和布洛赫本构参数理论预测值之间的误差很小, 这说明本文推导的布洛赫本构参数的理论计算公式在描述周期性磁谐振材料的电磁特性方面是十分有效的. 这些理论公式将在解释磁谐振现象、设计和优化周期性磁谐振材料等方面提供重要的理论依据.
关键词:
周期性结构
磁谐振
布洛赫本构参数
面磁流 相似文献
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A method is presented which allows to calculate the large signal beam efficiency of a gyromonotron working at the s-th harmonic of the cyclotron frequency. The results of this calculation using efficiency optimized parameters are given for different TEmn distributions and also for a magnetic taper. It is shown that beam efficiencies, which are higher than twice the value at constant electric and magnetic fields are theoretically possible. Also the influence of the beam voltage is considered. For a given beam voltage and a given electric field distribution in the resonator power calculations are performed and it is shown what powerlevels are available for different resonator modes and for different cyclotron harmonics. 相似文献
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A. N. Moroz A. N. Maksimova V. A. Kashurnikov I. A. Rudnev 《Physics of Atomic Nuclei》2019,82(11):1460-1465
A numerical investigation of the response of a HTS with different numbers of defects to the action of rectangular magnetic field pulses with a varying amplitude is carried out. The time dependences of a magnetic field trapped by the superconductor are calculated at different pulse parameters. The values of the HTS response to pulsed and gradual magnetization and demagnetization of the sample are compared, which reveals that magnetic flux trapping is more efficient under the action of pulses. A feature in the behavior of the vortex lattice acted on by field pulses is established, which relates to correlation between the number of defects and pulse amplitude. Flux trapping is shown to have a maximum dependent on the concentration of defects at each pulse amplitude. 相似文献
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分析了线圈杂散参数对高频下复磁导率测量的影响,指出绕组电阻、寄生电容及漏感会导致传统复磁导率测量方法在高频下误差增大。在此基础上提出了使用单匝全包结构进行复磁导率宽带测量的方法,该方法适用于400 MHz以下频率的复磁导率测量。介绍了复磁导率的常见模型,并分别使用Levy法及有理函数迭代逼近法(IRFA)进行模型参数提取,分析了两种算法的优缺点及应用范围。应用推荐复磁导率测量方法对三种磁性材料进行了复磁导率的测量和建模,结果表明,使用推荐的复磁导率测量方法及数据提取算法,可以较好地实现对磁性材料的小信号建模。 相似文献
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势阱中的类氢杂质的能级问题一直为学术界所长期关注。讨论了异质界面上中性施主D0和负施主离子D-的能量随垂直于界面的磁场的变化情况,同时将磁场和势阱结合起来考虑其对类氢杂质的影响。研究发现随磁场的增大,其对D0基态能的影响越来越大,对其束缚能的影响逐渐变小,而对D-中心,磁场的作用使得D-由非束缚态转变为束缚态。计算中分别选取了两种不同的波函数,分析了这两种波函数的适用范围,利用变分的方法得到此结构中D0中心的基态能量和束缚能与D-中心角动量L=-1自旋三重态的本征能量和束缚能随磁场的变化关系,找到了此三重态由非束缚态转变到束缚态对应磁场的阈值。 相似文献
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Magnetization dynamics in thin films and multilayers 总被引:1,自引:0,他引:1
R. E. Camley 《Journal of magnetism and magnetic materials》1999,200(1-3):583-597
The behavior of spin waves is influenced by essentially all the parameters which characterize a magnetic material – exchange interactions, anisotropy, surface effects, dipolar interactions, phase transitions and imperfections. Thus measurements of spin wave frequencies can give important information on characterizing different magnetic materials and structures. In this paper we outline the major results and calculational methods for long-wavelength spin waves in thin films and multilayers. While the primary attention is on ferromagnet-based structures, long-wavelength spin waves in antiferromagnets are also discussed. We indicate how particular measurements of spin wave frequencies can be used to extract the fundamental parameters of the different structures. 相似文献
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张建平 《核聚变与等离子体物理》2005,25(2):146-152
对于在仅有外加横向三角脉冲磁场下的悬臂导电薄板,给出了受到脉冲磁场影响时其动力稳定性的定量分析方法。揭示了在三角脉冲磁场下由于受到涡电流与总磁场相互作用所产生的面内磁体压力的作用,悬臂导电薄板会发生失稳。得到了在不同稳态磁场作用下受到三角脉冲磁场作用时导电薄板的磁弹性动力响应的数值模拟结果。在此基础上,给出了关于稳态磁场值、横向脉冲磁场峰值和脉冲持续时间等参数范围的磁弹性动力稳定性区域。 相似文献
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W. Delaney 《International Journal of Theoretical Physics》1974,10(4):239-251
A semiclassical model in which elementary particles are represented as systems of charged shells with associated quark-like quantum numbers is presented. Specifically the baryons are considered. Formulas are obtained which express baryon masses and magnetic moments in terms of model parameters which relate baryon and quark properties. Basically, the mass and moment formulas are expressions for mass ratios and magnetic moment ratios. Simple identifications for the model parameters lead to a prediction for the proton-electron mass ratio and to fairly accurate predictions for the baryon magnetic moments in units of the proton moment. The mass and moment formulas, which relate corresponding properties of different particles, are generalised such as to express relationships between the members of a sequence of particles, where such a sequence is conceived of as containing only one (normal) baryon. A specific sequence, containing the proton and electron, is proposed; various physical properties of the particles in the sequence are determined. In particular, a second prediction for the proton-electron mass ratio is obtained; the two predictions differ numerically but both agree with the measured value of the mass ratio within experimental error. 相似文献
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《中国物理 B》2019,(10)
Micromagnetic simulation is employed to study the gyration motion of magnetic vortices in distinct permalloy nanodisks driven by a spin-polarized current. The critical current density for magnetic vortex gyration, eigenfrequency, trajectory, velocity and the time for a magnetic vortex to obtain the steady gyration are analyzed. Simulation results reveal that the magnetic vortices in larger and thinner nanodisks can achieve a lower-frequency gyration at a lower current density in a shorter time. However, the magnetic vortices in thicker nanodisks need a higher current density and longer time to attain steady gyration but with a higher eigenfrequency. We also find that the point-contact position exerts different influences on these parameters in different nanodisks, which contributes to the control of the magnetic vortex gyration. The conclusions of this paper can serve as a theoretical basis for designing nano-oscillators and microwave frequency modulators. 相似文献
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Magnetic field distribution, expressed in terms of coil parameters (geometric and current), of various kind of ironfree current wire elements is derived. A method for shaping and adjusting fringing field profile by the use of separated current wires which have different coil parameters is suggested, and the optimization of coil parameters is realized by the use of the method of least square. As an example, magnetic field profile of an iron-free magnetic β-ray spectrometer is shaped and adjusted to illustrate the use of this method. 相似文献