Fe-Cu-Nb-Si-B纳米晶体软磁材料中有效磁各向异性的测定

研究了成分为Fe_73.5Cu₁Nb₃Si_13.5B₉的纳米晶体结构的软磁材料的磁各向异性。理论分析及测量结果说明,用趋近饱和的磁化过程可以测定出这种材料中的有效磁各向异性常数,它比晶粒中的磁晶各向异性常数K₁约小一个数量级。 关键词：     

非晶态合金Fe81B13.5Si3.5C2在退火过程中磁各向异性和晶化的穆斯堡尔研究

用穆斯堡尔谱和X射线衍射方法,研究了急冷非晶态合金薄带Fe₈₁B_13.5Si_3.5C₂在空气中退火时磁各向异性的变化,及其与表面结晶和整体结晶的相关性。实验表明,在空气中退火时,磁各向异性的反常变化亦与表面结晶向体结晶的发展密切相关。 关键词：     

金属玻璃在磁场张力退火时感生磁向各异性、磁致伸缩和应变的变化

本文通过同时测量金属玻璃Co_65.2Fe_4.2Ni₃Nb₁Al₂Si_9.8B_14.8的同一样品在各种横磁张力退火后的磁各向异性、磁致伸缩和应变,对这些物理量的变化情况作了比较。应变感生各向异性和暂态蠕变的行为有某种相似性,但其间不存在对应或因果关系。磁化感生各向异性K_um,应变感生各向异性K_us,饱和磁致伸缩常 关键词：     

非晶态铁基合金退火样品的偏移回线

报道了非晶态铁基合金(Fe_65.9Cr_11.6Si_7.5B₁₅和Fe₆₀Co_5.9Cr_11.6Si_7.5B₁₅)退火样品的回线偏移现象.研究了偏移回线与测量磁场H_m,温度T和时间t的关系.基于退火产生的硬磁颗粒与剩余非晶软磁母体之间的静磁相互作用机制,利用等效的单向各向异性模型可以很好地分 关键词： 铁基非晶合金 偏移回线 单向各向异性     

非晶CoFeNiNbSiB合金的巨磁阻抗效应

研究了非晶Co₇₀Fe_4.5Ni₄Nb₁Si_12.5B₈合金薄带的巨磁阻抗效应.实验表明,在一定频率范围内提高测试频率,磁阻抗效应有明显提高;适当温度的退火也有助于磁阻抗效应的提高.制备态非晶合金样品在频率为5MHz下达120%左右,经过退火处理的非晶样品5MHz下的效应可达400%左右. 关键词：     

金属玻璃(Fe1-xCox)78Si10B12的感生各向异性

本文研究了金属玻璃(Fe_1-xCO_x)₇₈Si₁₀B₁₂的磁化感生各向异性、应变感生各向异性随成分和温度的变化。磁化感生各向异性常数K_um为正值,x=0.7时为最大;不可逆的应变感生各向异性常数K_usi为正值,x=0.5时为最大;可逆的应变感生各向异性常数K_usr除了x>0.975区均为负值,在x=0.7时为最大;感生各向异性常数在温度变化时与M_s^α成正比,α在3.4和7.5之间随成分和退火工艺而变化。用短程有序模型解释了部分实验结果。 关键词：     

磁共振法研究(Fe1-xCox)84Zr3.5Nb 3.5B8Cu1纳米晶薄带的磁各向异性

铁磁共振（FMR）实验研究(Fe_1-xCo_x)₈₄Zr_{3.5 Nb3.5B8Cu1（x=0.0,0.2,0.4,0.6, 0.8）合金薄 带的各向异性，易轴在薄带的横向方向,同等宽度样品 的各向异性常数K′随Co掺杂量的增加而减小, K′值在4.67×10^-5　J/m（x=0. 0）到 2.54×10^-5　J 关键词： 铁磁共振 各向异性常数 低场非共振信号 磁化过程}     

Fe-Ni-Si-B非晶合金磁导率的等温时效

测试了制备态非晶(Fe_1-xNi_x)₇₆Si₈B₁₆合金在较低温度(65—150℃)下等温时效过程中磁导率的变化。结果表明:在65℃以下时效,磁导率变化不大;在100℃以上时效,磁导率发生了明显变化,此变化与合金成分有关。用应力、磁致伸缩和感生磁各向异性的变化对实验结果进行了圆满的解释。 关键词：     

退火处理Fe43Co43Hf7B6Cu1非晶合金的正电子湮没研究

对熔体急冷法制备的Fe₄₃Co₄₃Hf₇B₆Cu₁非晶合金进行了200,300,400和500 ℃保温30 min的退火处理,用正电子湮没寿命谱、X射线衍射、穆斯堡尔谱等方法研究了退火后试样的结构及结构缺陷变化.结果表明,在非晶合金的制备态,正电子主要在非晶基体相空位尺寸的自由体积中湮没,湮没寿命τ₁为158.4 ps,强度I₁关键词： 43Co₄₃Hf₇B₆Cu₁非晶')" href="#">Fe₄₃Co₄₃Hf₇B₆Cu₁非晶 退火处理 正电子湮没寿命 结构与结构缺陷     

纳米超微晶Fe73.5Cu1Mo3Si13.5B9合金显微结构和磁性的研究

对纳米晶Fe_73.5Cu₁Mo₃Si_13.5B₉合金的原始制备态和各退火态样品进行了室温Mossbauer谱研究,结果表明晶化态的合金存在α-Fe(Si)微晶相和晶界的非晶相。晶相和非晶相内场和面积随退火温度的变化是退火时Cu,Mo,B等成分的扩散和在各相中的再分配引起的。最佳磁性能对应非晶相中的铁量占合金铁总量的30％左右,超微晶合金的双相无规各向异性模型表明,一定量的非晶相对保持纳米晶优异的软 关键词：     

Torque magnetometer measurements of the temperature dependence of induced anisotropy energy and of saturation magnetization in amorphous Fe40Ni40P14B6

Induced anisotropy energy K_u and saturation magnetization M have been measured as a function of temperature T between 77 K and T_c on co$\text{n}$venient specimens of amorphous Fe₄₀Ni₄₀P₁₄B₆ by means of a torque magnetometer. The M vs. T curve is found to follow an anomalously low behaviour with respect to crystalline materials. The exper$\text{i}$mental K_u vs. T curve is well fitted by a M² law, also different from higher power laws typical of crystalline alloys.     

Brillouin scattering from ferromagnetic metallic glasses

We report the first measurements of thermally excited surface acoustic phonons, and bulk and surface magnons from metallic glasses using Brillouin scattering. In particular we present data on the compositions Fe₄₀Ni₄₀P₁₄B₆ and Fe₈₀B₂₀. The velocity of the surface phonons was found to agree within 1.5% with the value calculated from elastic continuum theory using known bulk elastic constants. The observed field dependence of the bulk magnon frequency can be fit within experimental error to the classical relation for the k = 0 mode by including alldemagnetizing corrections. The values for the magnetization obtained from both the surface and bulk magnons agree with the bulk values determined previously with a magnetometer. The measured field dependences of the surface magnon frequency allow us to determine the g-factors, yielding 2.08±0.02 for FeB and 2.03±0.03 for FeNiPB.     

Effects of oblique-incidence evaporation on magnetic properties of Fe20Ni80/Fe70Co30 bilayer film

Evaporative deposition at oblique incidence is shown to enhance the magnetic anisotropy of an Fe₂₀Ni₈₀ magnetic film and induce magnetic anisotropy in an overlying, strongly isotropic Fe₇₀Co₃₀ film. This deposition method for the formation of an underlayer of several lattice parameters in thickness and semi-hard overlayer of a few thousands Angstroms in thickness achieves a significant change in the magnetization process and strong suppression of the coercive forces of Fe₇₀Co₃₀ in the hard magnetization direction. Soft magnetization of the Fe₇₀Co₃₀ overlayer is not achieved when one of the layers is deposited at oblique incidence. It is anticipated that shape magnetic anisotropy is responsible in part for the magnetic anisotropy induced in both in Fe₂₀Ni₈₀ under- and Fe₇₀Co₃₀ overlayer by oblique incidence evaporation.     

A Simple Method of the Hyperfine Field Direction Estimation from the Moessbauer Experiment

A simple method is proposed for the estimation of the average hyperfine field, i.e. the magnetization direction in the foil samples from the ⁵⁷Fe Moessbauer spectra measured at three different orientations. The intensity ratios in the Moessbauer spectra of the sample perpendicular to the gamma-ray propagation direction and tilted by 45° in the longitudinal and transversal planes yield both angle coordinates of the hyperfine field direction without supposing the direction vector normalization, i.e., avoiding the necessity of line intensities corrections. The method is demonstrated by showing the influence of heat and mechanical treatments on the magnetization direction in two amorphous alloys, Fe₈₀Cr₂Bi₁₄S₄ and Fe₄₀Ni₄₀B₂₀, the latter showing a pronounced stress annealing induced magnetic anisotropy.     

Investigation of the magnetic characteristic of amorphous Fe40Ni40B20 and Fe6Co70Ni13Si7B4 foils by a magnetooptical method

Magnetic parameters, the local anisotropy field H_k, the effective field h related to the correlation radius, and the coercive force H_c, are determined for free and contact surfaces by investigating the magnetization curves of amorphous Fe₄₀Ni₄₀B₂₀ and Fe₆Co₇₀Ni₁₃Si₇B₄ foils by a highly-sensitive method of measuring the magnetooptical phase.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 49–52, November, 1989.     

Influence of structural defects on the magnetization process in high-magnetic fields in the Fe61Co10Y8Nb1B20 alloy in the form of ribbons and plates

Amorphous samples of the Fe₆₁Co₁₀Y₈Nb₁B₂₀ alloy in the form of a ribbon with thickness of approximately 30 μm and in the form of a plate with thickness of 0.5 mm have been investigated. Plates were obtained by a suction-casting method, and ribbons by a single roller melt-spinning method. Microstructural studies, using X-ray spectroscopy, confirmed that samples in the as-quenched state were fully amorphous. Measurements carried out using a vibrating sample magnetometer allowed values of coercivity and saturation magnetization to be obtained; it also facilitated the estimation of size and nature of structural defects in the investigated samples. All of the investigated samples of this alloy in the as-quenched state have high values of saturation magnetization of greater than 1.25 T.     

Modification of magnetic anisotropy in metallic glasses using high-energy ion beam irradiation

Heavy ion irradiation in the electronic stopping power region induces macroscopic dimensional change in metallic glasses and introduces magnetic anisotropy in some magnetic materials. The present work is on the irradiation study of ferromagnetic metallic glasses, where both dimensional change and modification of magnetic anisotropy are expected. Magnetic anisotropy was measured using Mössbauer spectroscopy of virgin and irradiated Fe₄₀Ni₄₀B₂₀ and Fe₄₀Ni₃₈Mo₄B₁₈ metallic glass ribbons. 90 MeV ¹²⁷I beam was used for the irradiations. Irradiation doses were 5×10¹³ and 7.5×10¹³ ions/cm². The relative intensity ratios D ₂₃ of the second and third lines of the Mössbauer spectra were measured to determine the magnetic anisotropy. The virgin samples of both the materials display in-plane magnetic anisotropy, i.e., the spins are oriented parallel to the ribbon plane. Irradiation is found to cause reduction in magnetic anisotropy. Near-complete randomization of magnetic moments is observed at high irradiation doses. Correlation is found between the residual stresses introduced by ion irradiation and the change in magnetic anisotropy.     

A comparative study of FMR and Brillouin light scattering on amorphous Fe40Ni40B20

It is shown that magnetic surface mode frequencies in the amorphous ferromagnet Fe₄₀Ni₄₀B₂₀ measured using Brillouin light scattering depend upon the incident laser light intensity: presumably due to local heating of the specimen due to the concentration of the light flux into a focal spot only a few microns in diameter. Surface mode frequencies extrapolated to zero light intensity are shown to be consistent with magnetic parameters measured using ferromagnetic resonance at 35.731 GHz to within ±0.5 GHz for specimens of amorphous Fe₄₀Ni₄₀B₂₀. 0.5 GHz corresponds to a change of 0.17 kG in the saturation magnetization, 4πM_s.     

The effect of internal stresses on the magnetization curve of amorphous ferromagnetic FeNi alloys

The Rayleigh region, the coercive field and the magnetization curves of the amorphous, ferromagnetic alloys Fe_80−xNi_xB₂₀ and Fe₄₀Ni₄₀P₁₄B₆ have been investigated as a function of the temperature and composition. It is shown that the characteristic parameters of the magnetization curves can be described by the statistical potential theory as developed previously for the movement of domain walls. Our experimental results are compatible with the assumption that the obstacles opposing the domain wall displacements are elastic stress centres produced during the rapid quenching process of the amorphous alloys.     

High-magnetic-field magnetization and magnetoresistance of some amorphous ferromagnets

Measurements of isothermal magnetization and magnetoresistance at T = 4.0-4.2 K and 15 ? H ? 132 kG on the amorphous ferromagnets Fe₈₀B₂₀, Fe₇₈Mo₂B₂₀, Fe₄₀Ni₄₀P₁₄B₆, and Fe₃₂Ni₃₆Cr₁₄P₁₂B₆ indicate a relatively large H-induced increase (3.6%) in the high-magnetic-field magnetization of the latter alloy, and marked differences in the magnitude and sign of the high-field magnetoresistance of the four alloys. The results are qualitatively interpreted in terms of internal effective field distributions which include a small fraction of atomic spins in negative field sites.