NiFeSiMnMo／Cu／NiFeSiMnMo多层膜的磁导率和巨磁阻抗比的研究

用磁控溅射方法制备NiFeSiMnMo/Cu/NiFeSiMnMo多层膜;理论研究了多层膜巨磁阻抗效应与磁导率的关系;实验研究了NiFeSiMnMo/Cu/NiFeSiMnMo多层膜结构的磁导率和巨磁阻抗比.在驱动频率3MHz下△μ′/μ′(%)出现800%的最大值,巨磁阻抗比出现14.4%的最大值.     

NiFeSiMnMo/Cu/NiFeSiMnMo多层膜中Cu层对巨磁阻抗效应的影响

在康宁玻璃上用真空蒸镀法沉积NiFeSiMnMo单层膜、NiFeSiMnMo/Cu双层膜和NiFeSiMnMo/Cu/Ni-FeSiMnMo多层膜.对单层膜和双层膜的软磁性能进行了分析,对多层膜的巨磁阻抗效应随Cu层宽度的变化进行了研究.实验研究表明,NiFeSiMoMn/Cu双层膜比NiFeSiMnMo单层膜矫顽力小、饱和磁化强度高;多层膜Ni-FeSiMnMo/Cu/NiFeSiMnMo随着Cu层宽度的增加巨磁阻抗比上升到一个最大值后下降,在磁性层宽度3mm的情况下,Cu层宽度在0.7mm时,巨磁阻抗比最大.     

NiFeSiMnMo/Cu/NiFeSiMnMo多层膜结构中磁性层厚度对巨磁阻抗效应的影响

在康宁玻璃上用真空蒸镀法沉积NiFeSiMnMo/Cu/NiFeSiMnMo多层膜,对所沉积单层膜的软磁性能随膜厚的变化和多层膜的巨磁阻抗效应随磁性层(NiFeSiMnMo)厚度的变化进行分析.实验结果表明:NiFeSiMnMo单层膜随厚度的增加,矫顽力增大,软磁性能变差;退火后的多层膜的纵向巨磁阻抗比(GMI ratio)的最大值随磁性层NiFeSiMnMo的厚度增加而增加.     

制备态FeZrBNi/Ag/FeZrBNi三层膜的巨磁阻抗效应

用射频溅射法在单晶硅衬底上制备了FeZrBNi／Ag／FeZrBNi三层膜,对制备态样品进行了磁阻抗测量．结果表明,样品纵向和横向的最大磁阻抗比分别为18％和31％,取得最大阻抗比的频率分别为7和8MHz;在此频率下,样品的纵向和横向相对磁导率比分别达到153％和5117％．这表明掺Ni的FeZrB三层膜在制备态已具备优异的巨磁阻抗效应和软磁性能．同时还分析了薄膜样品的电阻、电抗分量和有效磁导率随频率的变化关系．     

FeNiCrSiB/Cu/FeNiCrSiB膜的磁畴结构和巨磁阻抗效应

用高频溅射法制备了ＦｅＮｉＣｒＳｉＢ／Ｃｕ／ＦｅＮｉＣｒＳｉＢ膜,经３５０℃退火２０ｍｉｎ后得到性能优良的巨大磁阻抗材料,磁畴结构观察表明,样品中心为均匀的细条畴靠近边缘,磁畴方向转向横向,这种畴结构有利于磁力线的闭合,是获得显著的巨阻抗效应的重要原因之一,磁阻抗测量表明,样品在１３ＭＨＺ的频率下,分别获得了６３％和７％的纵向和横向磁阻抗比     

玻璃包覆钴基非晶细丝的巨磁阻抗研究

深入研究了玻璃包覆的成分为Ｆｅ６８．２５Ｃｏ４．５Ｓｉ１２．２５Ｂ１５,直径为２５ｕｍ的非晶细丝的巨磁阻抗效应。在频率为０．１～１２ＭＨｚ,磁场在０～５．２ｋＡ／ｍ的范围内测量了交流磁电阻、磁电抗、磁阻抗对频率及磁场的依赖关系。发现该细丝材料的巨磁阻抗ＧＭＩ（Ｚ）值在测量频率范围内随频率增大而增大。     

复合非晶丝的巨磁阻抗效应分析

研究了外层为NiFe层，里层为Ag丝的复合结构材料的巨磁阻抗效应，发现复合丝在较低频率下就有较大的阻抗变化值。同时推导了外场小于各向异性场时具有网周各向异性的复合丝的阻抗表达式，并讨论了各结构参量对巨磁阻抗效应的影响。发现材料的巨磁阻抗效应强烈依赖于复合丝铁磁层的厚度；而导体层和铁磁层的电导率相差越多则材料的巨磁阻抗效应也越大。     

矩形脉冲电流退火与激励电流对Co基非晶带巨磁阻抗效应的影响

利用矩形脉冲电流对Co_(66.3)Fe_(3.7)Si_(12)B_(18)非晶带进行退火处理,研究了退火电流密度对非晶带巨磁阻抗效应的影响,同时研究了激励电流频率对退火处理后的非晶带巨磁阻抗效应的影响。结果表明,该非晶带的特征频率为1.4 MHz。最大巨磁阻抗所对应的磁场随激励电流频率的增加逐渐向高磁场方向移动。     

复合焦耳处理对Co68.15Fe4.35Si12.5B15非晶薄带巨磁阻抗效应的影响

本文研究了复合焦耳处理对Co68.15Fe4.35Si12.5B15非晶薄带巨磁阻抗效应的影响。实验结果表明：经前段电流密度10A／mm^2,后段电流密度30A／mm^2的复合焦耳处理后样品获得了最大的GMI效应。在8MHz的交变电流频率下,最大磁阻抗比为217％,灵敏度为114％／Oe,比淬态下的最大磁阻抗比和灵敏度均有明显提高。复合焦耳处理是提高材料GMI效应的一种新型的而且十分有效的方法。     

退火工艺对Co71．8Fe4．9Nb0．8Si7．5815非晶薄带巨磁阻抗效应的影响

采用四端法研究了退火处理T艺对Co71.8Fe4.9Nb0.8Si7.5B15非晶薄带巨磁阻抗效应的影响.结果表明,Co71.8Fe4.9Nb0.8Si7.5B15非晶薄带试样经350 ℃保温60 min退火处理后,样品的内应力得到有效释放,大大改善了样品的软磁特性,得到了最大的巨磁阻抗效应(GMI).在8 MHz的交变电流频率下,得到了24%的最大磁阻抗比.XRD分析表明,样品发生晶化后将降低巨磁阻抗(GMI)效应.     

GIANT MAGNETO-IMPEDANCE OF PATTERNED FeSiB／Cu／FeSiB TRI-LAYER FILMS

Sensitive magnetic field sensor with good performances can be fabricated utilizing the giant magneto-impedance (GMI) effect of soft magnetic multi-layer thin films. The transverse and longitudinal GMI effect in patterned FeSiB/Cu/FeSiB tri-layer films with the change of external magnetic field and frequency were studied at the same time. The change of the impedance of the films with the external magnetic fieldand frequency was shown. Comparing the longitudinal and transverse effect, the transverse effect has a larger linear range from zero magnetic field to a quite large magnetic field at all frequencies, and the change still were not saturated until the external magnetic field reached 1.2×104A/m, which illustrated that the films can be utilized to detect larger magnetic fields than now presented GMI sensors.     

SOFT MAGNETIC PROPERTIES AND GIANT MAGNETOIMPEDANCE EFFECT IN MAGNETIC FIELD–DEPOSITED FeCuCrVSiB FILMS

采用射频溅射法, 在无磁场和施加72 kA/m的纵向磁场下制备了FeCuCrVSiB软磁合金薄膜样品, 对沉积态样品的软磁特性和巨磁阻抗(GMI)效应进行了测量和分析. 结果表明, 在制备过程中加磁场可明显改善材料的软磁性能, 与无磁场沉积态相比, 样品的矫顽力从1.080 kA/m降低到0.064 kA/m, 在13 MHz频率下有效磁导率比从10%增加到106%. GMI效应与磁导率比的大小密切相关. 无磁场沉积态样品没有检测到GMI效应, 而磁场沉积态样品则具有显著的GMI效应. 在13 MHz 的频率下, 最大纵向和横向巨磁阻抗比分别高达22%和20%. 这些结果都优于厚度几乎相同的退火态FeCuNbSiB薄膜的GMI特性.     

沉积态(Fe88Zr7B5)0.97Cu0.03软磁合金薄膜的磁性和巨磁阻抗效应

采用射频溅射法在单晶硅衬底上制备了(Fe88Zr7B5）0．97Cu0．03非晶软磁合金薄膜样品，对沉积态样品的软磁性能和巨磁阻抗(GMI)效应进行了实验研究与机理分析．结果表明，未掺Cu元素的Fe88Zr7B5沉积态合金薄膜几乎无GMI效应，而掺了适量Cu元素的(Fe88Zr7B5)0．97Cu0．03合金薄膜在沉积态下即具有显著的GMI效应．在13MHz频率下，最大纵向磁阻抗比达17％，最大横向磁阻抗比为11％，这表明(Fe88Zr7B5)0．97Cu0.03非晶合金薄膜在沉积态已具备优异的软磁性能和巨磁阻抗效应．同时讨论了该薄膜样品的巨磁阻抗效应随频率的变化特性．     

磁场沉积态FeCuCrVSiB薄膜的软磁特性和巨磁阻抗效应

采用射频溅射法,在无磁场和施加72 kA/m的纵向磁场下制备了FeCuCrVSiB软磁合金薄膜样品,对沉积态样品的软磁特性和巨磁阻抗(GMI)效应进行了测量和分析.结果表明,在制备过程中加磁场可明显改善材料的软磁性能,与无磁场沉积态相比,样品的矫顽力从1.080 kA/m降低到0.064 kA/m,在13 MHz频率下有效磁导率比从10%增加到106%.GMI效应与磁导率比的大小密切相关.无磁场沉积态样品没有检测到GMI效应,而磁场沉积态样品则具有显著的GMI效应.在13 MHz的频率下,最大纵向和横向巨磁阻抗比分别高达22%和20%.这些结果都优于厚度几乎相同的退火态FeCuNbSiB薄膜的GMI特性.     

Giant magnetoimpedance effect in Fe-Zr-Nb-Cu-B nanocrystalline ribbons

The giant magnetoimpedance effect of the nanocrystalline ribbon Fe84Zr2.08Nb1.92Cu1B11 (atom fraction in %) was investigated. There is an optimum annealing temperature (TA=998 K) for obtaining the largest GMI (giant magneto-impedance) effect in the ribbon Fe84Zr2.08Nb1.92Cu1B11. The ribbon with longer ribbon length has stronger GMI effect, which may be connected with the demagnetization effect of samples. The frequency fmax, where the maximum magnetoimpedance GMI(Z)max =[(Z(H)-Z(O)/Z(O)]max occurs, is near the intersecting frequency fi of the curves of GMI(R), GMI(X), and GMI(Z) versus frequency. The magnetoreactance GMI(X) decreases monotonically with increasing frequency, which may be due to the decrease of permeability. In contrast, with the AC (alternating current) frequency increasing, the magnetore-sistance GMI(R) increases at first, undergoes a peak, and under then drops. The increase of the magnetoresistance may result from the enhancement of the skin effect with frequency. The maximum magnetoimpedance value GMI(Z)max under H=7.2 kA/m is about -56.18% at f= 0.3 MHz for the nanocrystalline ribbon Fe84Zr2.08Nb1.92Cu1B11 with the annealing temperature TA=998K and the ribbon length L=6cm.     

Influence of Aspect Ratio on Giant Magnetoimpedance Effect for Fe_(67)Co_(18)Si_(11)B_4 Amorphous Ribbons

The effect of sample geometry aspect ratio(l/w)on the giant magnetoimpedance(GMI)in Fe_(67)Co_(18)Si_(11)B_4amorphous ribbons was investigated systematically.The GMI profiles were measured as a function of the external magnetic field at different frequencies up to 110 MHz.The results show that there exists a critical aspect ratio((l/w)_0=5.4)below which the maximum GMI effect and sensitivity g decrease with decreasing l/w and above which the maximum GMI effect keeps almost constant and g decreases with increasing l/w.The observed dependence on aspect ratio as(l/w)\(l/w)_0is correlated with the magnetization process:Complex domain structures emerged near the ribbon ends to decrease the magnetostatic energy,modify the transverse permeability and consequently GMI response.Contributions from transverse permeability and resistance may dominantly determine the change of GMI effect as(l/w)[(l/w)_0.