张应力对FeCoSiB非晶薄膜磁特性的影响

采用磁控溅射方法,在弯曲的玻璃基片上制备出受张应力作用的FeCoSiB非晶薄膜,研究了张应力大小对FeCoSiB薄膜的磁畴、矫顽力、剩磁、各向异性场等磁特性的影响.结果表明,薄膜的畴结构显著依赖于张应力,其磁畴宽度随张应力增加而增加;张应力导致FeCoSiB薄膜内形成较强的磁各向异性,其各向异性随应力的增大而增大.     

柔性FeCoSiB非晶磁弹性薄膜的应力阻抗效应

采用直流磁控溅射方法在柔性Kapton基片上沉积了FeCoSiB薄膜,研究了偏置磁场、溅射气压以及测试频率对薄膜应力阻抗效应的影响规律.结果表明,本文中优化的溅射气压为1.5 Pa,强的偏置磁场可形成强的横向各向异性,从而显著提高材料的应力阻抗效应.随着测试频率从0.1MHz升高到30 MHz,薄膜的应力阻抗效应显著增强.     

溅射气压对FeCoSiB非晶薄膜表面形貌及磁特性的影响

利用磁控溅射的方法，在玻璃基片上制备了FeCoSiB非晶薄膜，研究了溅射心气压强对薄膜表面形貌及磁特性的影响。结果表明，薄膜的表面形貌显著依赖于心气压强，随着山Ar压强的增加，薄膜表面颗粒增大，粗糙度增加并形成柱状微结构。心气压强对薄膜磁特性有显著的影响，随血压强增加，薄膜的矫顽力增加，而剩磁则呈下降趋势。从薄膜的磁滞回线、矫顽力以及剩磁随溅射气压的变化规律可知，溅射气压较小时制备的薄膜软磁性能较好．     

热处理温度对FeCoSiB薄膜及FeCoSiB/Cu/FeCoSiB三明治膜应力阻抗效应的影响

采用DC磁控溅射法在玻璃基片上制备了FeCoSiB薄膜和FeCoSiB/Cu/FeCoSiB 三明治膜,并进行磁场退火热处理以消除残余应力和形成磁织构,提高薄膜的应力阻抗效应。薄膜的磁性能采用振动样品磁强计(VSM)进行测试,采用HP4275A 型阻抗分析仪在200kHz~10MHz频率范围内测试薄膜的应力阻抗效应。结果表明,磁场退火热处理可形成感生磁各向异性,改善薄膜的软磁性能、提高薄膜的应力阻抗效应。在温度低于300℃时,随着退火温度的增加,薄膜的应力阻抗效应增大;当退火温度超过300℃时,薄膜的应力阻抗效应随退火温度增加而降低。与Fe CoSiB单层膜相比, FeCoSiB/Cu/FeCoSiB 三明治膜应力阻抗效应较大。10MHz测试频率下,在基片末端位移为450μm时,经300℃热处理的三明治膜达到了8.3%,而单层膜仅有1.86%。当测试频率较高为10和4MHz时,薄膜的应力阻抗效应变化不大,当测试频率下降到低于1MHz时,薄膜的应力阻抗效应显著降低。     

应力对非晶超磁致伸缩薄膜形变影响的理论计算

分析材料磁化过程中引起磁致伸缩的机理,考虑应力对磁化过程的影响,通过将应力作用等效为磁场,并假设非晶超磁致伸缩薄膜的低场磁化为可逆过程,根据能量最低原理,建立了磁致伸缩薄膜形变与应力之间的关系,给出了表达式.     

（BiAl）YIG薄膜的生长感生磁各向异性

从理论和实验上分析了Ｆｅ＾３＋和Ｆｅ＾２＋对（ＢｉＡ）ＹＩＧ薄膜的生长感各向异性的贡献，掺Ｂｉ导致的生长磁感生各向异性，来源于Ｅｉ＾３＋改变了Ｆｅ＾３＋的零场劈裂，其大小取决于Ｂｉ＾３＋含量及在十二面体位的择优分布，高价离子和氧空位形成的Ｆｅ＾２＋在八面体位的择优分布，对生长感生磁各向异性也有贡献。     

非晶FeCoSiB薄带的压磁性能研究

采用单辊法制备非晶FeCoSiB薄带,并进行退火处理以消除残余应力,提高薄带的压磁效应.采用4294A型阻抗分析仪在40Hz～100MHz频率范围内测试薄带的压磁效应.结果表明,退火可使薄带内部产生磁各向异性,消除内应力,提高薄带的压磁性能.在退火低于300℃时,薄带压磁效应随着退火温度的增加而增加;但当退火温度高于300℃后,薄带压磁效应随着退火温度的增加而降低.当温度为300℃时,退火时间也会对薄带的压磁性能产生影响,在退火时间低于1h时,薄带压磁效应随着退火时间的增加而增加;但当退火温度高于1h后,薄带压磁效应随着退火时间的增加而降低.非晶FeCoSiB薄带的经过300℃×1h退火后,测试频率为100MHz﹑压力为1.42MPa时,阻抗变化可达3.38Ω,压磁性能最佳.     

FeCoSiB/Cu/FeCoSiB多层膜的应力阻抗效应研究

采用直流磁控溅射法在柔性Kapton基片上制备了三明治结构的FeCoSiB/Cu/FeCoSiB多层膜,研究了多层膜的交流阻抗随外加应力变化的规律.测试结果表明,三明治结构多层膜的阻抗随外加应力的增大而增大,应力阻抗效应随中间导电层厚度以及铁磁层厚度的增加而增强,同时应力阻抗效应也与测试频率密切相关.     

退火效应对非晶TbFeCo薄膜磁性能的影响

详细研究了退火效应对非晶TbFeCo薄膜磁滞回线的影响。 10 0℃退火表明 ,薄膜保留较大的垂直磁各向异性、矫顽力和很好的矩形比 ,磁致伸缩各向异性是引起矫顽力下降的主要原因。经 13 0℃退火显示 ,矫顽力和垂直磁各向异性明显下降 ,薄膜仍展示垂直于膜面的矫顽力和磁滞回线 ,但是薄膜显示一清晰的平面内磁各向异性。实验表明 ,矫顽力和垂直磁各向异性的大大降低只是与退火温度的升高有关 ,而长时间的退火并不能有效影响薄膜的磁性和矫顽力。     

非晶FeSiB薄膜中的巨磁阻抗效应

采用射频溅射法在三组不同溅射条件下制备了ＦｅＳｉＢ薄膜。测量了溅射薄的磁滞回线，并利用ＨＰ４１９４Ａ阻抗分析仪，在１－４０ＨＭｚ频率范围内研究了样品的巨磁阻抗效应。     

Magnetic anisotropy control in amorphous FeCoSiB films by stress annealing

It is important to control magnetic anisotropy of ferromagnetic materials. In this work, magnetic anisotropy of amorphous FeCoSiB films is controlled by stress annealing. FeCoSiB films are deposited on glass substrate and annealed with stress in vacuum. When the annealed films are released from clamp, permanent tensile or compressive strain can be introduced in the films. Influences of both tensile and compressive strain on the magnetic properties of FeCoSiB films have been studied. The results show that FeCoSiB films by stress annealing exhibit strong magnetic anisotropy while the samples by normal annealing exhibit magnetic isotropy. Easy axis along the stress is induced in the films with tensile stress, while easy axis perpendicular to the stress is induced in the samples with compressive stress. It has also been found that the magnetic anisotropy increases with the increase of the strain. The effects of strain on the magnetic properties of FeCoSiB films have been interpreted by stress induced anisotropy via magnetoelastic coupling.     

Evidence for selective resputtering as the growth mechanism of pair-order anisotropy in amorphous TbFe films

Processing conditions for rf magnetron sputter-deposited amorphous TbFe films in which an atomic scale structural anisotropy (ASSA) results as a natural consequence of selective resputtering at the film surface during growth are presented. The ASSA, measured using polarization-dependent X-ray absorption fine structure with quantitative modelling via a parametrized nonlinear least squares fitting, is described as a pair order anisotropy (POA) where a statistical preference exists for like atom pairs in-plane and unlike atom pairs perpendicular to the film plane. The perpendicular magnetic anisotropy (PMA) energy increases with increasing POA for samples grown using decreasing rf power and increasing working gas pressure. The POA directly reflects the anisotropic electrostatic environment at the rare earth site which is required for PMA to result from a single ion anisotropy mechanism.     

Effects of MgO and MgO/Pd seed-layers on perpendicular magnetic anisotropy of CoPd thin films

We studied the effects of MgO and MgO/Pd seed-layers on perpendicular magnetic anisotropy in co-sputtered CoPd films. CoPd films with the MgO seed-layer showed perpendicular magnetic properties that were superior to those with another after annealing. The loop squareness was unity, indicating strong perpendicular magnetic anisotropy, when the MgO seed-layer was thicker than 2 nm. We observed that the out-of-plane CoPd (111) texture was strongly developed, as well as the in-plane tensile stress in the CoPd films. The magnetoelastic anisotropy coming from a negative magnetostriction λ₁₁₁ under the in-plane tensile stress dominating over other anisotropies is likely responsible for creating such strong perpendicular magnetic anisotropy. In the case of the MgO/Pd seed-layer, the CoPd films showed mixed anisotropy having both in-plane and out-of-plane magnetic anisotropy components after annealing. The appearance of the strong (100) texture of the CoPd films with the MgO/Pd seed-layer is believed to have caused the decrease in the perpendicular magnetic anisotropy that originated from the magnetoelastic anisotropy due to the additional contribution from the positive magnetostriction λ₁₀₀ but less contribution from the negative magnetostriction λ₁₁₁ when the CoPd films are under in-plane tensile stress.     

FeNHf软磁薄膜中磁各向异性对太赫兹波调控的研究

本文制备了具有磁各向异性的纳米FeNHf软磁薄膜,表征了FeNHf薄膜的微结构、磁性能、微波磁动力学行为和磁各向异性对太赫兹波传输特性的影响.FeNHf薄膜的难轴方向具有410的磁导率,易轴方向没有磁导率信号,磁各向异性场为2537.65 A/m.FeNHf薄膜在1.04 THz时出现了共振吸收峰,当调控磁化强度方向分...     

直径对玻璃包覆非晶合金微丝磁性的影响

采用Taylor-Ulitovsky方法制备了直径分别在6.3～28.0μm、20.2～28.0μm和14.0～35.2μm之间的玻璃包覆非晶态FeCuNbVSiB、FeBSiCMn和CoNiFeSiB微丝。通过X射线衍射、扫描电镜、振动样品磁强计分别测试了玻璃包覆微丝的组织结构、微观形貌和磁性,研究了不同成分玻璃包覆磁性合金微丝的玻璃包覆层厚度、合金芯直径对微丝磁性能的影响。结果表明了,玻璃包覆磁性合金微丝的磁性能的影响因素由大到小依次为：饱和磁致伸缩系数、微丝成分和微丝尺寸。轴向磁化时随着微丝直径及玻璃包覆层厚度的增大,3 种微丝的径向饱和场强度降低,FeCuNbVSiB和FeBSiCMn微丝的轴向矫顽力先分别由508 A/m和390 A/m降低到486 A/m和278 A/m后再升高到2570 A/m和342 A/m,CoNiFeSiB微丝的轴向矫顽力由171 A/m降低到63 A/m。     

Influence of magnetic annealing on high-frequency magnetic properties of FeCoNd films

FeCoNd thin film with thickness of 166 nm has been fabricated on silicon (1 1 1) substrates by magnetron co-sputtering and annealed for one hour under magnetic field at different temperatures (T_a) from 200 °C to 700 °C. The As-deposited and annealed FeCoNd film samples at T_a ≤ 500 °C were amorphous while the ones obtained at T_a ≥ 600 °C were crystallized. We found that the perpendicular anisotropy field gradually decreases as the annealing temperature increases from room temperature to 300 °C. A well induced in-plane uniaxial anisotropy is achieved at the annealing temperature between 400 and 600 °C. The variation of the dynamic magnetic properties of annealed FeCoNd films can be well explained by the Landau-Lifshitz equation with the variation of the anisotropy field re-distribution and the damping constant upon magnetic annealing. The magnetic annealing might be a powerful post treatment method for high frequency application of magnetic thin films.     

Induced magnetic anisotropy and strain in permalloy films deposited under magnetic field

Field induced magnetic-anisotropy is a very important but poorly understood property. There have been many hypotheses on the origin of the phenomenon, e.g. strain, atomic pair ordering, etc., but little experimental evidence exist. This study prepares 100 nm thick Permalloy films having the field-induced-magnetic-anisotropy and carefully measure strains, i.e. interplanar distance of crystallographic (111) planes in various directions, using high power synchrotron radiation and precise Grazing Incidence X-Ray Diffraction method. The result delineates that the field-induced-magnetic-anisotropy has a strong correlation with the strain-anisotropy in the film.