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本文针对坡莫合金椭圆形盘中的磁涡旋结构, 采用微磁学模拟与傅里叶分析相结合的技术研究了磁涡旋自旋波的本征激发模式. 通过沿样品短轴方向施加一面内方向的脉冲磁场, 观察到一系列方位角自旋波模式. 观察到的自旋波模式具有两重对称性, 可以通过C2群理论来进行类型的划分. 此外, 自旋波模式的频率随着方位角指标的变化而线性增加. 模拟结果显示样品的平均交换能量密度明显的高于平均静磁能量密度; 局域交换能量密度主要集中在涡核初始位置, 而局域静磁能量密度主要分布在长轴附近. 交换作用对受限于铁磁薄膜椭圆盘中的单个涡旋态的能量要起主导作用, 从而导致方位角自旋波模式频率随着方位角指标的增加而增加. 相似文献
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分析了斜向静磁场作用下磁光薄膜波导中传播的静磁正向体波特性,计算了YIG薄膜波导中静磁波传播常数以及与磁光耦合系数相联系的动态磁化强度对静磁波模数、频率和斜向场等的依赖关系.计算表明:静磁波频率f及模数m越大、磁场Hi及其偏角θ越小,静磁波传播常数Ks越大;零模静磁体波的(动态磁化强度)振幅远大于高模数的静磁体波振幅.在适当的静磁体波频率范围内,斜向偏置磁场可提高静磁体波的振幅,进而可以改善静磁波与导波光的相互作用特性和提高导波光的衍射效率.
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内禀磁性测量中的热磁扫描方法和SPD技术 总被引:2,自引:0,他引:2
一、引言在实验教学和科研活动中常常会遇到具有磁性的材料,需要分析和研究其磁性质,因此必须首先测量材料的磁晶各向异性场H_A、饱和磁化强度M_s和居里温度T_c等内禀磁性。其中测定H_A的传统方法是通过测量取向样品的磁化曲线来确定,此处我们介绍一种简便且精度很高的测量方法——奇点探测法(Singular Point Detection,简称SPD技术)。而居里温度T_c可以用振动样品磁强计、磁天平等在弱磁场中进行测量,饱和磁化强度M_s用提拉法装置,采用 相似文献
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设计了一种原波频率500 kHz、差频范围1~30 kHz的截断宽带参量阵,作为水声材料测量系统的声源。通过分析典型频率下的宽带参量源指向性理论计算和实际测量结果,发现两者结果的曲线基本吻合,证明计算模型是正确的。应用钟形短时脉冲实现水声材料声特性的宽带测量,有益于降低样品边缘衍射干扰。并建立了测量水声材料大面积板状样品声压反射系数、声压透射系数和吸声系数的压力罐测量系统,罐体内尺寸Φ4 m×12 m,最高静水压4.5 MPa,测量频率范围1~30 kHz。对标准样品(尺寸1m×1m)进行了测量实验,其测量结果和理论曲线有很好的吻合,参量源测量法得到了验证;之后,通过对一块橡胶板样品在不同静压力下的吸声性能进行了测量和有效评估,进一步确认了参量源测量法在压力罐这样有限水域中的潜在应用价值。 相似文献
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本文对比研究了超导材料磁测量中的SQUID法和Campbell法; 并用高压PIT法制备的超导材料MgB2作为测量样品,用两种方法,测量了超导样品的临界电流密度, 分别得到了样品的Jc-B关系曲线; SQUID法测量样品的外磁场可以达到6 T, 此时材料已经处于失超状态,此方法测得的结果是样品各个小区域结果的平均值, SQUID还可以用来进一步标度材料的钉扎力行为,研究材料磁特性. Campbell法测量只能测量到外磁场强度为0.4 T,外磁场的交流部分的频率可以达到800 Hz, 用这种测量方法得到的是整块样品的电流,由于测量计及材料内部微观结构缺陷等影响电流传输因素, 所测结果小于直流磁化法,但更切近材料实际电流,能用来深入研究材料内部结构差别对材料电性能的影响. 相似文献
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In addition to the general dispersion equation for surface-localized magnetic polaritons and magnetostatic waves, which propagate in the system antiferromagnetic superlattice-antiferromagnet, we derive a simplified result for the long-wavelength limit λ?L (L is the period of superlattice) when the superlattice is found to behave like an anisotropic bulk medium (effective-medium approach). The dispersion curves and frequency region of the existence of the surface magnetic polaritons and magnetostatic waves are presented numerically for several values of the external magnetic field and for different antiferromagnetic materials. 相似文献
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The dispersion relation of magnetostatic waves tangentially magnetized to saturation ferrite film, with a “magnetic wall” condition (tangential component of microwave magnetic field is equal to zero) on one of the film surface and with a metal condition on the opposite surface is analyzed. The dispersion characteristics show that unidirectional magnetostatic waves appear in this structure: they can transfer energy in one direction only and fundamentally cannot transfer energy in the opposite direction. The dispersion-free propagation of magnetostatic waves also is possible in the structure in a wide frequency interval. 相似文献
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We consider the Sagnac effect in ring interferometers on magnetostatic and surface acoustic waves. It is shown that the Sagnac
effect for waves of arbitrary type (including both magnetostatic and surface acoustic waves) propagating in an arbitrary medium
cannot be calculated using Galilean transformations but is explained within the framework of the special relativity and is
related to the difference between the phase velocities rather than group velocities of counter-propagating waves in the rotating
reference frame. We also show that the phase difference of counterpropagating waves due to the Sagnac effect depends on neither
the phase velocity of the wave in a medium at rest nor the dispersion of the medium; it depends only on the wave frequency
and the angular velocity of interferometer rotation. The minimum angular velocity that can be measured in the ring interferometers
using magnetostatic and surface acoustic waves is estimated.
N. I. Labachevsky State University, Institute of Applied Physics of the Russian Academy of Sciences, Nizhny Novgorod, Russia.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 42, No. 4, pp. 373–382, April 1999. 相似文献
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Effects of the resonant Bragg scattering of magnetostatic backward volume waves on the periodic structure of a conductive
meander pattern with an alternating current are analyzed theoretically and compared with experiment. It is shown that unlike
a static grating, a dynamic grating causes a frequency shift of the scattered wave. It is proposed that this phenomenon be
utilized for effective control of the intermodal conversion of magnetostatic waves.
Zh. Tekh. Fiz. 68, 105–112 (May 1998) 相似文献
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Yu. I. Bespyatykh I. E. Dikshtein V. P. Mal’tsev S. A. Nikitov V. Vasilevskii 《Physics of the Solid State》2003,45(11):2160-2165
The general regularities of the evolution of the spectrum of magnetostatic waves in a periodic system composed of alternating ferromagnetic and nonmagnetic layers are analyzed. The spectrum of electromagnetic waves in an infinite periodic system and the coefficient of reflection of a plane electromagnetic wave from a half-space periodically filled with ferromagnetic and nonmagnetic layers are calculated. The dispersion relation is derived and analyzed for surface magnetostatic waves at the interface between the periodic system of layers and vacuum. 相似文献
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S. A. Odintsov A. V. Sadovnikov A. A. Grachev E. N. Beginin Yu. P. Sharaevskii S. A. Nikitov 《JETP Letters》2016,104(8):563-567
Features of the propagation of magnetostatic waves in a tangentially magnetized magnonic crystal structure based on iron–yttrium garnet with a two-dimensional array of grooves on the surface are studied. Numerical simulation is performed by the finite element method and the dispersion characteristics and the spatial distribution of fields of eigenmodes of surface magnetostatic waves propagating in this structure are calculated. The characteristics of waves in the magnonic crystal structure are experimentally studied by means of Brillouin scattering. It is shown that the formation of waveguide channels is possible when the frequency of the input signal is close to the frequency of the band gap of the structure. 相似文献
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M. M. Shabat 《International Journal of Infrared and Millimeter Waves》1994,15(10):1651-1662
The general propagation characteristics of magnetostatic surface waves guided by a single interface of a semi-infinite nonlinear dielectric cover and a ferromagnetic substrate (YIG) have been derived. The nonlinear dielectric cover has intensity dependent refractive indices. The magnetostatic approximation is considered and retardation is ignored in describing the electromagnetic fields in the structure. The used magnetostatic approximation is leading to new waves and might be called nonlinear magnetostatic surface waves. The propagation of these waves is non-reciprocal in contrast to the linear magnetostaic surface waves, which had been only found in the negative direction of propagation. 相似文献
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Wideband chaotic microwave oscillation in a ring self-oscillatory system is studied. The system includes a solid-state power amplifier and a wideband nonlinear transmission line with a ferromagnetic film in which magnetostatic waves of different types are excited. It is found that the eigenmodes of the self-oscillatory system excited in the passband of the transmission line on magnetostatic waves become noisy because of spin wave parametric excitation due to the magnetostatic wave and nonlinearity of the power amplifier. A continuous spectrum of modes observed in the wideband chaotic signal is associated with the presence of a descending portion in the dynamic characteristic of the nonlinear transmission line, which arises when a magnetostatic surface wave is excited. 相似文献
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A device for holding biomolecule samples on a membrane allows scanning using terahertz frequency waves. Such scanning has previously been difficult due to the strong attenuation of terahertz frequency waves by water. Several types of biomolecules were scanned using terahertz time domain spectroscopy (TDS), and the data showed clear differences in transmittance among the samples. This membrane device is a promising aid for research on biomolecules using terahertz waves. 相似文献
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Interaction between two (small and large) regular microwave signals that simultaneously pass through a resonance transmission line based on backward volume magnetostatic waves is studied experimentally in different frequency ranges. It is found that the amplitude-frequency response of the small signal near the frequency of the large one depends on the frequency of the latter; namely, the amplitude of the small signal is affected by spin-wave packets parametrically excited by magnetostatic and electromagnetic pumps. 相似文献