自旋波共振激发的新模型

本文研究了磁性薄膜中的自旋波共振激发现象。在Portis体不均匀(Ⅵ)模型的基础上,提出了非对称体不均匀(AⅥ)模型和表面-体不均匀(s-Ⅵ)模型,很好地解释了实验研究中所观察到的线性自旋波谱,在这些谱中偶奇次模被同时激发,其强度按各自不同的包络线变化。 关键词：     

铁磁/反铁磁双层薄膜自旋波共振谱

本文在一维海森堡模型的基础上,采用界面参数化方法,研究了铁磁/反铁磁双层薄膜中自旋波低温激发问题．重点讨论了表面各向异性对薄膜中自旋波共振谱的影响．结果表明：体系中的自旋波本征模存在共振行为,表面各向异性场对体模、完全禁闭模的共振谱影响较大,对界面模没有影响．     

铁磁/反铁磁双层薄膜自旋波共振谱

本文在一维海森堡模型的基础上,采用界面参数化方法,研究了铁磁/反铁磁双层薄膜中自旋波低温激发问题．重点讨论了表面各向异性对薄膜中自旋波共振谱的影响．结果表明：体系中的自旋波本征模存在共振行为,表面各向异性场对体模、完全禁闭模的共振谱影响较大,对界面模没有影响．     

横场伊辛铁磁薄膜的自旋波

本文在格林函数理论的框架内,研究横场伊辛铁磁薄膜系统的自旋波,分析了横场、表面特性等薄膜参数对自旋波频谱及谱强度分布的影响,证实在一定的参数条件下可以出现一致进动模和局域的表面模。 关键词：     

异质双层磁性薄膜中自旋波的波形演化

在一维海森堡模型的基础上,采用界面参数化方法,将双层异质磁薄膜中自旋波本征值问题归结为联立求解能量约束方程和界面参数化方程.重点讨论体系中体模和完全禁闭模的波形演化过程,发现体系中体模波形随自旋波矢呈余弦变化,会出现局域共振现象.激发能对两子层中体模有较大的影响,不仅影响体模的振幅,而且还影响体模的波长.另外,激发能对体系中的完全禁闭模也有较大影响,随着激发能增大,铁磁层中完全禁闭模波长变短,波速变小,但振幅不变.     

异质双层磁性薄膜中自旋波的波形演化

在一维海森堡模型的基础上,采用界面参数化方法,将双层异质磁薄膜中自旋波本征值问题归结为联立求解能量约束方程和界面参数化方程．重点讨论体系中体模和完全禁闭模的波形演化过程,发现体系中体模波形随自旋波矢呈余弦变化,会出现局域共振现象．激发能对两子层中体模有较大的影响,不仅影响体模的振幅,而且还影响体模的波长．另外,激发能对体系中的完全禁闭模也有较大影响,随着激发能增大,铁磁层中完全禁闭模波长变短,波速变小,但振幅不变．     

磁场及体各向异性对面心立方双层铁磁薄膜能带的影响

利用二次量子化方法研究了由相同面心立方结构(100)材料构成的铁磁性双层薄膜,重点讨论了磁场及体各向异性对面心立方双层铁磁薄膜能带的影响.结果表明,无论界面为铁磁性界面交换作用或反铁磁性界面交换作用,磁场及各向异性场对对称薄膜中的自旋波存在方式及整个能带形状没有影响,只是影响整个激发模的能量.磁场和各向异性常数越大,自旋波能量越高.     

面心立方双层铁磁薄膜中低能量体模的波形演化

利用二次量子化方法研究了由相同面心立方结构(100)材料构成的铁磁性双层薄膜中的自旋波,重点讨论了低能量体模的波形演化情况.结果表明,面心立方晶格能量较低的体模在薄膜A-A型铁磁材料传播过程中波形完全相同,传播行为也完全相同;并且随着能量的增加,体模波长在两层铁磁薄膜材料中逐渐缩短,波速逐渐减小.     

量子自旋波本征值及易轴型各向异性对其的影响

本文考虑体单轴各向异性利用界面重参数化方法从理论上严格推导了两层异质铁磁质中量子自旋波的本征值,并模拟计算了简立方晶格结构 (100) 第一布里渊区的能带结构,特别研究了易轴型体单轴各向异性对本征值的影响.结果发现在这样的体系中存在体模、禁闭模和界面模;各种本征模与体交换作用、界面交换作用、晶格自旋、原子层数有关,而且各向异性直接影响各种本征模的存在条件. 关键词： 铁磁薄膜 自旋波 各向异性     

自旋I=3/2核四极共振体系对梳状脉冲的响应

用密度矩阵理论和计算机模拟较详细地讨论了自旋I=3/2核四极共振(NQR)粉末体系对梳状脉冲的响应以及偏共振效应的影响.在偏共振强度(包括谱线的非均匀增宽)较小的条件下.由它获得的谱与二维章动谱是相似的.但是实验所需时间能够减少近两个数量级. 关键词：     

Spin-wave resonance spectra of films with a uniform gradient of anisotropy field

It has been shown that the number of high-intensity spin-wave modes in the spin-wave resonance spectrum of films with a uniform gradient of the effective anisotropy field depends on the thickness of the film and on the exchange stiffness. It has been established that there is a “critical” thickness of the film which depends on the exchange stiffness and the anisotropy field gradient. When the thickness of the film is less than the “critical” value, only one high-intensity mode is excited in the resonance absorption spectrum.     

Angular dependences of spin-wave resonance spectra of inhomogeneous films with orthorhombic anisotropy

Zero spin-wave mode in inhomogeneous magnetic films with orthorhombic anisotropy has been found to exhibit a change of its localization region in two of three typical angular dependences of resonance fields of high-intensity modes. It has been shown that the anisotropy fields on both sides of the film can be determined from the resonance fields of the zero and uppermost high-intensity spin-wave modes of spin-wave resonance spectra.     

SSWR in conducting films with variable driving field symmetry

Intensities of antisymmetric (A) and symmetric (S) SSWR modes in a conducting film are calculated in plane-wave approximation and in simple one-mode approximations. Very good agreement between the two results is obtained for the integral intensities (i.e. resonance-line areas). Relations between the intensities of A and S modes detected experimentally in small films are interpreted taking into account thee field of surface charges occuring on film edges in A modes. Functional dependence of the A intensity on the spin-pinning parameterK _s indicates that SSWR spectra should be observable even in films with very smallK _s.     

Spin-wave resonance in [Co x Ni1 − x ]N and [Co x P1 − x ]N gradient films

Gradient films of ferromagnetic 3d metals with prescribed magnetic potential profile along the film thickness are obtained. It is found that the spin-wave resonance spectrum in these films is characterized by anomalous dependences of resonance fields of spin-wave modes H _r on the mode number: H _r(n) ～ n, H _r(n) ～ n ^2/3.     

Excitation, generation, and propagation of soliton-like spin-wave pulses in ferromagnetic films: Numerical calculation and experiment

The excitation, collision, and detection of soliton-like spin-wave pulses in ferromagnetic films are numerically simulated. The theoretical dependence of the pulse peak power at the output of the delay line on the peak power at the input of the input transducer is constructed for the first time. The experiment is compared with measurements. The shape of the nonlinear magnetization pulse excited and propagating in the film is theoretically studied as a function of the carrier frequency position relative to the backward volume spin-wave (BVSW) spectrum. The head-on collision of soliton-like BVSW pulses in ferromagnetic films is simulated for the first time.     

Collinear light scattering on dipole-exchange spin waves in inhomogeneous ferromagnetic films

A theory is developed for the collinear TE-TM scattering of optical waveguide modes on dipoleexchange spin waves in perpendicularly magnetized ferromagnetic films that are inhomogeneous across their thickness. It is found in homogeneous ferromagnetic films and in films with small deviations from homogeneity that the TE-TM scattering on higher spinwave modes is strongest when the synchronism conditions for the transverse phases and for the longitudinal and transverse wave vectors are satisfied. When the thickness of the planar optical waveguide does not match the thickness of the ferromagnetic film, the phase synchronism condition is violated with the resultant appearance of an oscillating type of dependence of the TE-TM scattering on the spin-wave mode number. The scattering of light on spin-wave modes in films with a magnetization gradient is investigated in the presence of turning points for the magnetostatic potential. It is found that the existence of a turning point in the region of the antinode for the optical modes leads to an increase in the scattering amplitude. The formation of inhomogeneous magnetooptical structures and superlattices based on (Lu,Y,Bi)₃(Fe,Ga)₅O₁₂ is discussed. Zh. Tekh. Fiz. 68, 78–84 (June 1998)     

有限铁磁—反铁磁线链中的自旋波谱及其激发

本文研究了由交换作用耦合起来的有限长铁磁和反铁磁链组成的自旋系统。计算了系统的自旋波的波谱及其在微波场中的激发强度。在所得结果的基础上,讨论了具有反铁磁氧化层的铁磁薄膜的自旋波共振。阐明了等效地使用唯象普遍边界条件的可能性。根据理论,对等效的表面各向异性能作了估计,得到的数值与实验值很好地符合。     

Interaction of macroparticles localized in Wigner–Seitz cells of various types of cubic lattices in an equilibrium plasma

The factors affecting the slope of the dispersion curve of the spin-wave resonance spectrum in multilayer films are determined. It is shown that an increase in the slope of the curve for the transverse orientation of the constant magnetic field relative to the film upon an increase in frequency is due to enhancement of dynamic as well as dissipative mechanisms of spin pinning. It is found that an increase in the damping parameter increases the degree of spin pinning in the case when the pinning layer is a reactive medium for spin oscillations and can decrease the degree of pinning when it is a dispersive medium. The conditions ensuring a higher degree of accuracy in determining the exchange interaction constant from the spin-wave resonance spectrum in multilayer films are determined.     

Regularities in penetration of electromagnetic waves through metallic magnetic films

Penetration of millimeter electromagnetic waves through permalloy films under magnetic resonance conditions is studied experimentally and theoretically. Measurements are taken on film samples from 40 to 200 nm in thickness in a frequency range from 26 to 38 GHz. Magnetic resonance, antiresonance, and spin-wave resonance are observed. The resonance spectrum is reconstructed. The Gilbert damping constant is determined for a series of films. It is shown that the damping constant decreases upon an increase in the film thickness. The resonance line profile is calculated, and the dependences of resonance line amplitude and width on experimental conditions and material parameters of the film are determined.