Cr底层对DyCo薄膜磁性能与结构影响研究

采用磁控溅射法制备了DyCo/Cr非晶垂直磁化膜.振动样品磁强计(VSM)测试结果显示,有无Cr底层的DyCo薄膜都具有垂直磁各向异性,加入Cr底层能将DyCo薄膜的矫顽力从163kA/m提高到290kA/m.薄膜断面扫描电镜(SEM)照片可以看出,Cr底层能够诱导上层的DyCo薄膜形成柱状结构.这一柱状结构导致了薄膜矫顽力的提高.     

多孔氧化铝模板上TbFeCo薄膜的制备及磁性能

利用两步阳极氧化方法在玻璃基板上成功制造孔洞排列有序的多孔氧化铝基底,实验结果表明,孔洞大小范围在10～50nm,孔洞大小可通过氧化电压和氧化温度进行调节,随氧化电压和温度降低而减小.多孔氧化铝底层对其上溅射生长的TbFeCo磁性能有重要影响,多孔氧化铝基底对TbFeCo的畴壁运动有较强的钉扎作用,增大其矫顽力,矫顽力随孔洞的直径增大而减小,从15nm时的4.5×105A/m下降到40nm时的2.8×105A/m,并逐步趋近无AAO膜板时TbFeCo的矫顽力.同时多孔氧化铝基底的引入,使TbFeCo薄膜的矫顽力机制从以磁晶各向异性为主改变为以形状各向异性为主.     

溅射工艺条件对TbFeCo/Pt薄膜磁性能的影响

采用射频磁控溅射法在玻璃基片上成功制得了TbFeCo/Pt非晶垂直磁化膜,系统研究了溅射工艺参数对TbFeCo薄膜磁性能的影响.振动样品磁强计测量结果表明:Tb含量在补偿成分点附近,采用较低的溅射氩气压与Pt底层,有利于提高TbFeCo薄膜的磁性能;当Tb含量为0.24,溅射功率为300W,溅射气压为0.53Pa,薄膜厚度为140nm时,TbFeCo/Pt薄膜矫顽力达到476kA/m,饱和磁化强度为151kA/m,剩磁矩形比超过0.8,该薄膜有望用作高密度光磁混合记录介质.     

FePt/B4C垂直磁记录介质薄膜的制备与表征

采用直流及射频磁控溅射结合真空退火的方法成功制备了（001）择优生长的FcPt/B4C多层薄膜并对其结构与磁性能做了初步的表征．结果表明，在每一个FbPt单元层中能得到较好（001）面择优的fet相FbPt合金，并且随着B4C含量的增大，薄膜的有序度提高．高分辨透射电子显微镜及其傅立叶变换表明，FePt层为具有（001）织构的fct相Fe55Pt45合金．样品的M-H曲线显示其垂直膜面方向矫顽力约为302.481kA/m；平行膜面方向矫顽力很小．     

FePtAg-C纳米颗粒薄膜的制备及表征

采用磁控溅射法在硅基片上生长FePt纳米颗粒薄膜。在硅片表面生长MgO籽层用来引发FePt合金薄膜的fct织构,加入C来减小其颗粒尺寸,加入Ag来增强其L10有序度。采用X射线衍射仪（XRD）、超导量子干涉仪（SQUID）和高分辨率透射电镜（TEM）对FePt薄膜进行表征。结果表明制备的薄膜样品具有优良的L10相结构,其M-H曲线表明方形度很好,垂直矫顽力HC有2467 kA/m,颗粒大小为10.4 nm。该薄膜非常适合用做下一代高密度磁存储媒质,可有效提高信息存储密度。     

脉冲电压沉积制备金属Ni纳米线阵列及磁性能

以硫酸溶液为电解质,采用两步电化学阳极氧化法制备了氧化铝有序多孔膜,孔径为20nm,孔间距为50nm左右,孔洞密度为4.5×1010个/cm2.以此多孔膜为模板,以脉冲信号为沉积电压制备了金属Ni纳米线阵列,单根纳米线直径为15～20nm,择优取向为Ni(220)晶面.磁滞回线结果表明垂直于膜面的方向为易磁化方向,当磁场垂直于膜面时,矩形比高达90.5%,矫顽力为63.84kA/m.     

Ag底层对TbFeCo薄膜磁性能的影响

采用射频磁控溅射法在玻璃基片上制备了TbFeCo/Ag非晶垂直磁化膜，研究了Ag底层厚度对TbFeCo薄膜磁性能的影响。原子力显微镜、振动样品磁强计与磁光盘测试仪测量结果表明：薄的银底层具有较高的表面粗糙度可以显著增大TbFeCo薄膜的矫顽力，改善TbFeCo薄膜的磁光温度特性，该薄膜有望用作高密度垂直记录介质与光磁混合记录介质。     

不同退火时间对[Ag/FePt]_(10)多层膜磁性能和微结构的影响

采用射频磁控溅射的方法,在玻璃基片上制备了不同Ag层厚度的[Ag/FePt 2nm]10多层薄膜,经550℃真空热处理后,得到L10有序结构的FePt薄膜.实验结果显示,FePt单层薄膜经550℃退火30min后其易磁化轴处于垂直方向和面内方向之间,而550℃退火60min后其易磁化轴处于垂直于膜面方向,垂直矫顽力和面内矫顽力分别为634和302kA/m;真空退火后[Ag/FePt]10多层膜表现为面内磁晶各向异性,550℃退火60min后[Ag 2.8nm/FePt 2nm]10多层薄膜垂直矫顽力和面内矫顽力分别为309和778kA/m,并且随着Ag层的加入,部分FePt颗粒已经被Ag原子隔开了,颗粒之间的交换耦合作用变弱了.     

阳极氧化铝膜的制备和磁性纳米阵列

目的 为了获得一定的纳米孔排列结构。方法 采用了电化学阳极氧化法制备氧化铝纳米结构。可以得到具有不同参数的密集排列的六角形结构膜,其中的纳米孔具有高绘横比。结果 我们制备了阳极氧化铝膜,而后得到了Ｆｅ纳米阵列,从磁滞回线讨论了它的垂直磁化特性。结论 以阳极氧化铝膜为模板,在其中沉积磁性纳米颗粒,可以得到了磁性纳米阵列,它具备高的垂直磁化特性。     

含核壳异质结构6.5% Si高硅钢铁芯的制备与磁性能

以构建高磁感、低铁损、免轧制高硅电工钢铁芯为出发点,提出采用单辊甩带制备非晶铁硅合金薄带、微氧化法在铁硅合金粉末表面包覆高电阻率铁硅氧化物薄膜制备核壳异质结构高硅电工钢纳米粉末、放电等离子烧结快速成形制备颗粒间绝缘的高硅电工钢铁芯。研究了不同氧化包覆时间对SPS烧结试样密度、物相组成、微观结构和静磁性能的影响。研究表明,在氧化包覆5h烧结温度800℃工艺条件下,制备的6.5%Si高硅电工钢铁芯的静磁性能最佳,饱和磁化强度为128.84A.m2/kg、矫顽力为2.25kA/m、剩磁为3.47A.m2/kg。其饱和磁化强度与粉末压延法制备的高硅钢相当,但矫顽力降低了1/3。     

Study on Micro-magnetic Simulation of Magnetic State of TbFeCo/Anodized Aluminum Oxide Film

Based on the experimental study of the AAO underlayer??s effect on the magnetic properties and structure, combining micro-magnetic theory as well, TbFeCo/AAO film magnetic properties and magnetic reversal characteristics were analyzed by finite-element micro-magnetic calculation software Magpar. With limited hardware conditions for the computer, a TbFeCo perpendicular magnetization films model with 9×9 matrix particles was simulated. It was found that for the pinning effect of non-magnetic porous AAO barrier film on TbFeCo particle film, the coercivity of isolated TbFeCo/AAO film (2100 kA/m) was larger than the coercivity of continuous TbFeCo film (2000 kA/m). The exchange coupling among the film particles, which was affected by AAO barrier film, led to a longer magnetization reversal time of isolated TbFeCo films than that of continuous ones.     

铝阳极氧化膜纳米孔阵列的微细结构

用电化学阳极氧化法制备了纳米多孔铝阳极氧化膜(AAO模板).采用原子力显微镜(AFM)测试AAO膜,研究了纳米孔阵列的形成机制.结果表明,在AAO膜的表面,除存在六方形的纳米孔阵列外,在孔端还存在六个微小的隆起,相邻的隆起之间彼此相连,看上去酷似一朵盛开的梅花,花的中心就是六方形纳米孔.二维AFM图像显示,以往用扫描电镜表征的纳米孔阵列,实际上是一幅排列整齐、并呈周期性变化的梅花阵列图案.膜背面阻挡层的AFM二维图像表明,膜胞呈六方形,且排列高度有序.膜胞密度为4.3×109/cm2,与孔密度基本一致.阻挡层的三维照片显示,膜胞的底部存在半球状突起,也呈现出规整的阵列图案.     

One-step anodization fabrication and morphology characterization of porous AAO with ideal nanopore arrays

A fabrication method for one-step anodization of an anodic aluminum oxide (AAO) template with nanopore arrays using pretreated high purity aluminum foil is reported in this article. Morphology of the AAO was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Results showed that porous AAO with ideal nanopore arrays can be fabricated by one-step anodization fabrication technology on high purity aluminum foil which had been anodized at 45?V direct current (DC), in 0°C, 0.5?M H₂C₂O₄ solution for 48 hours. The average pore diameter and the interpore distance were 80?nm and 120?nm, respectively. Nanopores in porous AAO had very narrow size distribution and were arranged into hexagonal array. The formation mechanism of nanopore arrays in porous AAO is discussed. Porous AAO with ideal nanopore arrays provide an ideal template for preparation of many one-dimensional nanomaterials. One-step anodization of AAO is a simpler procedure and more applicable in industrial application than the previous two-step anodization technology.     

掺杂Mg对纳米CoFe2O4/SiO2复合薄膜结构和磁性的影响

采用溶胶-凝胶旋涂法制备了纳米Co_1-xMg _xFe₂O₄/SiO₂(x = 0, 0.2, 0.4, 0.6, 0.8) 复合薄膜。利用XRD、SEM、原子力显微镜、振动样品磁强计对薄膜的结构、形貌和磁性进行了分析, 研究了Mg²⁺含量对样品结构和磁性的影响。结果表明, 样品中Co_1-xMg _xFe₂O₄具有尖晶石结构, 晶粒尺寸在38~46 nm之间。随着Mg²⁺含量的增加, Co_1-xMg _xFe₂O₄的晶格常数减小, 样品的饱和磁化强度减小, 矫顽力先增大后减小。样品Co_0.4Mg_0.6Fe₂O₄/SiO₂垂直和平行膜面的矫顽力分别为350.7 kA·m^-1和279.4 kA·m^-1, 剩磁比分别为67.2%和53.9%, Co_1-xMg _xFe₂O₄/SiO₂复合薄膜具有较明显的垂直磁各向异性。     

Magnetic properties and microstructures of single-layered Fe100 − xPtx films deposited onto heated substrates

The single-layered Fe_100 − xPt_x films of 30 nm thick with Pt contents (x) of 35-57 at.% are deposited on heated Si (100) substrate at a temperature (Ts) of 620 °C by magnetron co-sputtering. When the Pt content in the Fe-Pt alloy film is 35 at.%, the value of in-plane coercivity (Hc_//) is close to perpendicular coercivity (Hc_⊥) and both values are about 800 kA/m. The FePt films exhibit perpendicular magnetic anisotropy when the Pt content increases to the values of between 45 and 51 at.%. The perpendicular coercivity, saturation magnetization (Ms) and perpendicular squareness (S_⊥) for Fe₅₄Pt₄₆ film are as high as 1113 kA/m, 0.594 Wb/m² and 0.96, respectively. These magnetic properties reveal its significant potential as perpendicular magnetic recording media. Upon further increasing the Pt content to 57 at.%, the coercivity of the Fe-Pt film decreases drastically to below 230 kA/m and tends to be closer to in-plane magnetic anisotropy.     

Structure, morphology and magnetic properties of Fe-B-Si-Nb glassy alloy thin film prepared by a pulsed laser deposition method

With the aim of applying to a soft magnetic underlayer of the double-layered perpendicular magnetic recording media, an Fe_74.9B_17.5Si_2.5Nb_5.1 alloy thin film was fabricated on Si substrate by a pulsed laser deposition method. The Fe-based alloy thin film of 200 nm in thickness was confirmed as a glassy structure. The thermal properties of the thin film have similar features to those for the melt-spun glassy alloy ribbon. The glassy alloy thin film exhibits good soft magnetic properties, i.e., high B_s of 1.2 T and in-plane low H_c of 134 A/m. The Fe-B-Si-Nb glassy alloy thin film is expected to be suitable for the soft magnetic underlayer material in the double-layered perpendicular magnetic recording media.     

Magnetic Properties of Percolated Perpendicular FePt–MgO Films

Percolated perpendicular FePt-MgO films with a (Fe₄₈ Pt ₅₂)_100-x-(MgO)_x/Pt(001)/Cr(002) structure were prepared by conventional dc magnetron sputtering (x=0-6.13). Magnetic measurements demonstrate that the coercivity of the magnetic film drastically increases from 169 to 285 kA/m as the MgO content is increased from 0 to 0.15 vol.%. However, the grain sizes of the FePt phase do not significantly varying upon doping with MgO. MgO does not appear at the grain boundaries of the FePt phase, but is present as crystalline dots that are uniformly precipitated in the FePt matrix. The MFM images revealed that the domain structure transformed from extending to isolate when the MgO dots precipitated into the FePt grains. Consequently, the MgO dots serve as pinning sites of the domain wall and enhance perpendicular coercivity. Percolated perpendicular magnetic recording is thus regarded as a solution to the problem of thermal instability in ultrasmall grains     

六角晶格多孔Si纳米阵列的制备研究

采用AAO模板7LAr＋磨技术在Si基片上合成了大面积规则的六角纳米孔阵列,阵列六角晶格尺寸及纳米孔深度可由H3PO4扩孔时间、氧化电压、离子磨时间等工艺参数精确控制。孔间距、孔直径与工艺参数的关系为ID=15．8＋2．17V和蹄0．905V＋0．452TH-20,其中V为氧化电压,TH为H3PO4扩孔时间;孔深度则可被控制为：Y=27．59T-5．44X＋21．76,X为AAO模板长径比,T为离子磨时间。该制备方法将可广泛应用于高效荧光发光器件、太阳能光伏器件、气体传感器件和THz受激辐射等光电子器件。     

Influence of initial growth layer and Ti underlayer on magneticproperties and recording characteristics of very thin films ofevaporated Co-Cr media

A Co-Cr film deposited directly on a substrate has an initial growth layer with low coercivity. However, the existence of a Ti underlayer prevents the formation of such a layer. As a result, Co-Cr film deposited on a Ti underlayer has high perpendicular anisotropy and coercivity even in cases of extremely thin film thickness (200 Å). As for the read-write characteristics of Co-Cr thin-film media, the existence of such an initial growth layer greatly improves the reproduced output level. The cause for this is considered to be that the free charges which appear on the back surface of the perpendicular recording layer are reduced and the demagnetization field acting on the recorded magnetization subsequently decreases due to the existence of the initial growth layer