TbFeCo缓冲层对钴铁氧体薄膜的微观结构和磁性能影响

采用射频磁控溅射技术在非晶TbFeCo缓冲层上制备了钴铁氧体(CoFe2O4)薄膜,并在空气中于300～1 000℃退火.采用X射线衍射仪、振动样品磁强计对薄膜的微观结构和磁性能进行表征.研究表明:样品均以单相尖晶石结构存在.在300℃退火时具有(111)择优取向;而高于300℃退火时薄膜的(111)择优取向逐渐消失;在800℃以上退火时出现(400)择优取向.所有薄膜均具有高矫顽力和高垂直各向异性,800℃退火样品垂直于膜面方向具有最大矫顽力832×103A/m,矩形度为0.73,900℃退火时矩形度达0.9.     

高密度硬磁盘用Ba铁氧体薄膜

本研究应用对向靶溅射装置（FTS）制备Ba铁氧体薄膜，并对该膜进行热处理，研究了成膜时的基板温度对热处理后的结晶构造及磁特性的影响。研究结果得知，通过热处理薄膜得以晶化，而且结晶构造是随成膜时的基板温度而变化的。在室温下制成的薄膜，其矫顽力大体与500℃下成膜的矫顽力相等，约为239kA／m（3kOe）。另外，基板温度300℃时制成的薄膜，其矫顽力在119kA／m（1．5kOe）以下。成膜时的基板温度影响热处理后的结晶构造及磁特性，室温下形成的薄膜可能具有作为高密度磁记录介质更为优异的磁特性     

Sm(Co_(bal)Ni_(0.18)Fe_(0.1)Zr_(0.04))_x的永磁薄膜性能的研究

稀土永磁合金薄膜在微机电系统(MEMS)、磁记录介质、自旋电子元件和医疗科学领域有着重要的应用。Sm Co基永磁薄膜,其内禀居里温度高于其他永磁薄膜,高温条件下有更高的稳定性,因而在MEMS中具有潜在的应用前景。采用复合靶和纯钐靶共溅射制备出Sm Co基永磁薄膜样品,研究了薄膜合金中Sm含量以及退火温度等对Sm(CobalNi0.18Fe0.1Zr0.04)x相结构、微观形貌以及磁性能的影响,得出以下结论:退火温度对薄膜织构也有明显影响。随着退火温度提高,薄膜织构增强,矫顽力提高。随着Sm含量的提高,薄膜中Sm Co相析出增多,组织更加均匀,矫顽力明显提高。     

SmCo(Al,Si)/Cr薄膜磁性能的温度稳定性

用磁控溅射方法结合高温退火的方法在玻璃基片上制备了一种高矫顽力 SmCo(Al,Si)/Cr结构的磁性薄膜,其矫顽力达到 385.48 kA/m(4844 Oe)。研究其在 15℃到 350℃的范围内的磁性能与温度的关系。发现矫顽力随温度单调减小,而剩磁随温度的增加开始是减少的,在 90℃左右达到极小值。然后随温度的增加,在 190℃附近达到极大值。随后温度继续增加,剩磁逐渐减小。     

射频溅射CoCr双层膜及软磁盘的研究

本研究利用射频溅射法制备了垂直磁记录用正CoCr单层膜及NiFe/CoCr双层膜。研究了溅射压力Prf、基板温度Tsb对CoCr合金层(002)面△θ50角,矫顽力Hc⊥、Hc∥有效各向异性场HK*及正方比S⊥、S∥的影响。可以控制溅射条件使单层CoCr膜(002)面△θ50在5°以内,双层膜CoCr层△θ50在10°以内,而在较宽的范围内调整Hc⊥、Hc∥值。选择一定溅射条件制备了NiFe/CoCr双层膜软盘,并利用市售普通纵向记录的51/4英寸软盘机驱动装置及其环形磁头对该盘进行了读写实验,表明可以实现垂直方式的写入和读出。     

CoFe2O4纳米颗粒的溶液合成及磁性能

以Co(NO3)2.6H2O和Fe(NO3)3.9H2O为原料,采用直接溶液合成法制备CoFe2O4纳米粉体。分析了纳米粉体的物相结构、微观形貌及合成机理,研究了热处理温度对粉体磁性能的影响。结果表明:所得CoFe2O4粉体为立方尖晶石铁氧体,颗粒细小、分散均匀,平均粒径约为5nm。500℃以下热处理的粉体表现出良好的超顺磁性;500℃以后,随热处理温度上升,颗粒尺寸变大,粉体的比饱和磁化强度Ms、比剩余磁化强度Mr和矫顽力Hc均增大。室温下CoFe2O4粉体的Ms为3.4A.m2/kg。当热处理温度为900℃时,Ms增大到59.5A.m2/kg,Hc增大到97.0kA/m。     

掺银磁铁矿复合薄膜的制备及室温磁电阻效应

采用溶胶-凝胶技术结合旋涂法,以聚乙烯醇作为鳌合剂,选择适当的退火程序,制备了由金属Ag相和Fe3O4相所组成的Agx(Fe3O4)1-x=0,0.1,0.2,0.3)复合薄膜.磁力显微镜观察表明,Fe3O4晶粒为单畴颗粒,其直径为75～85 nm,小于理论计算的单畴,临界尺寸.磁性测量表明:x=0.1和0.3薄膜的矫顽力坼分别为23.1 kA/m和28.6 kA/m,很接近于Fe3O4的磁晶各向异性场HK(27.1 KA/m).室温(300K)下,x=0.1的薄膜具有最大的磁电阻,700 kA/m磁场下为-3.5%,高于纯Fe3O4薄膜的低场磁电阻(-2.2%).随着Ag含量进一步增加,薄膜的室温磁电阻减小.适量金属Ag的掺入有利于提高Fe3O4薄膜的磁电阻,这归因于自旋极化电子在Fe3O4晶粒和Ag颗粒界面处的自旋相关散射以及穿过Fe3O4-Fe3P4晶界的自旋极化隧穿的共同作用.     

电沉积制备Co-Pt-Mo磁性薄膜

通过电沉积方法在铜基底上制得Co-Pt-Mo磁性薄膜。通过对镀液的循环伏安分析,确定了合适的沉积电位。研究了pH值对薄膜的成分、表面形貌、结构以及磁性能的影响。结果表明:随着pH值的增大,薄膜中Co的质量分数从26.9%逐渐增加到63.8%,矫顽力与比饱和磁化强度分别从0.3kA/m和189kA/m增加到24.1kA/m和1 283kA/m。     

溶胶-凝胶法Ba铁氧体薄膜的磁特性与微观结构

用溶胶-凝胶法制备Ba铁氧体薄膜，并对其磁特性与微观结构的关系进行了研究。结果表明，（1）根据Ba铁氧体的化学计量成分，采用富Ba的涂布液（Fe／Ba=4～8），在800～900℃下进行晶化热处理的方法，可获得239～399kA／m（3～5kOe）的水平矫顽力；（2）随着Fe／Ba比的缩小，Ba铁氧体粒子微细化。在Fe／Ba=4～6的条件下，可得到10×100nm的针状粒子；（3）粒子间的磁相互作用微弱，磁化反转尺寸与针状粒子相同     

斜入射蒸镀铁膜的磁性和结构

<正> 斜入射真空蒸镀的金属或合金磁性薄膜具有很高的矫顽力和矩形比,是适用于高密度的磁记录材料。图1是我们采用真空蒸发得到的铁膜的Hc与入射角θ的关系,当入射角为80度时,Hc约为800Oe,Br/Bs≥0.85。高角度入射的铁膜之所以具有高的矫顽力,通常认为是由于晶粒沿着入射束方向排列所导致的形状各     

Electrodeposition of hard magnetic films and microstructures

Electrochemical deposition of materials with hard magnetic properties in the as-deposited state is essential for the efficient integration of micro-magnetic components into MEMS devices. Here we discuss the growth process and the microstructure-magnetic properties correlation for two Co-rich alloys, Co-Ni-P and Co-Pt. Under suitable synthesis conditions, these materials exhibit perpendicular anisotropy and hard magnetic properties in the as-deposited state; in addition, such properties are maintained up to several micrometer film thickness through close control of the film microstructure. In the case of Co-Ni-P films we achieved a saturation magnetization of 1.21 T (963 emu/cm³), perpendicular coercivity up to 188 kA/m (2.36 kOe) at a thickness of 10 μm, and energy products up to 4.2 kJ/m³. Co-rich Co-Pt films were grown on several substrates - Cr, Cu(0 0 1), Cu(1 1 1), and Ru(0 0 0 1) - in order to control magnetic anisotropy and achieve optimum hard magnetic properties. Cu(1 1 1) contributes to stabilize the hexagonal hcp phase at high current density yielding excellent hard magnetic properties, although only in films thicker than 100 nm; saturation magnetization in these films was about 1.04 T (828 emu/cm³). Perpendicular coercivities up to 485.6 kA/m (6.1 kOe) were obtained in 1 μm thick film deposited at 50 mA/cm². Ru(0 0 0 1) seed layers provide an appropriate interface structure to further facilitate the epitaxial growth of hcp films, yielding hard magnetic properties and perpendicular coercivity with a squareness ∼1 in films as thin as 10 nm. The hard magnetic properties were only marginally compromised at large film thickness. Deposition at higher current density (50 mA/cm²) favored markedly improved hard magnetic properties. The Co-Pt films on Ru exhibited perpendicular anisotropy with anisotropy constant up to 1.2 MJ/m³. The electrodeposition process was further extended to fill lithographically patterned hole arrays (850 nm diameter, center-to-center distance 2550 nm and about 700 nm thick resist), yielding arrays of micron-sized hard magnetic cylinders with perpendicular coercivity of 361 kA/m (4.54 kOe) and high squareness.     

膜厚对GdTbFeCo非晶薄膜磁光性能的影响

采用射频磁控溅射法在玻璃基片上制备了GdTbFeCo非晶薄膜,通过调节溅射时间制备出了不同厚度的薄膜,并研究了膜厚对薄膜磁光性能的影响。磁光特性测试仪的测试结果表明:溅射功率为75W,溅射气压为0.5Pa,薄膜厚度为120nm时,可以使GdTbFeCo薄膜垂直方向矫顽力和克尔角达到较大值,分别高达4575.476Oe和0.393o。能满足磁光记录材料矫顽力大,磁光克尔角大的要求。     

Fabrication of magnetic nanodot array using electrochemical deposition processes

We investigated fabrication processes of magnetic nanodot arrays for the ultra-high density magnetic recording media by using an electrodeposition. A CoZrNb underlayer was sputter-deposited on a glass disk substrate as a soft magnetic underlayer (SUL). Nano-patterns were formed on the substrate by UV-nanoimprint lithography (UV-NIL) and CoPt was electrodeposited into the nano-patterns. For obtaining uniform CoPt nanodot arrays with high perpendicular coercivities, we applied thin Cu intermediate layer on CoZrNb SUL and minimized its thickness. As a result, we obtained CoPt nanodot arrays with 150-nm diameter, 300-nm pitches, and 20-nm heights, which have uniform structures, on the substrates with the construction of Cu (1-2 nm)/CoZrNb (100 nm)/Cr (5 nm)/glass disk. The perpendicular coercivity of the CoPt nanodot arrays was as high as 5.4 kOe. From these results, we showed that the Cu intermediate layer with even 1-2 nm thick considerably improved the deposition condition on the substrates with CoZrNb SUL to successfully fabricate CoPt nanodot arrays with the diameter and pitches of 80 nm and 160 nm with sufficient uniformity.     

Preparation of high magnetic flux density CoNiFeB film by electroless deposition for application to magnetic recording devices

A CoNiFeB soft magnetic thin film with high saturation magnetic flux density (B_s) for use as a magnetic recording head core material or as a soft magnetic underlayer of a double perpendicular magnetic recording medium was prepared by electroless deposition. When the CoNiFeB alloy thin film was deposited on a evaporated Cu (100 nm thick)/glass substrate, the saturated magnetic flux density was found to increase up to 2.0 T by increasing the concentration of FeSO₄. The coercivity (H_c) was found to decrease to 6 Oe while the saturated magnetic flux density was maintained higher than 1.8 T by optimizing the concentrations of tartaric acid and citric acid in the electroless plating solution. An X-ray diffraction (XRD) study showed that the intensity of the assigned peak in the bcc (1 1 0) of CoNiFeB film decreased as the concentration of tartaric acid was decreased. Moreover, the coercivity of the CoNiFeB film formed on a NiFe substrate exhibits lower coercivity than that formed on a Cu substrate.     

L10 FePt Nanoparticles Processing with Applied Magnetic Field

Due to the strong magnetic anisotropy energy, the L1₀ FePt nanocrystals are considered as one of promising candidates for magnetic recording media with ultrahigh densities. The surfaces of Si and SiO₂ wafers have been covered by FePt nanoparticles (NPs) and heated at 600 °C for 1 h to form the L1₀ phase. Bonding of NPs with the SiO₂ surface in the presence of magnetic field during annealing process controls the L1₀ FePt NPs size and their uniform surface distribution. In the presence of perpendicular magnetic field to the surface, the size of NPs obtains up to 30 nm with coercivity of 5.8 kOe and in parallel magnetic field, the NPs size reaches to 45 nm with coercivity of 2.9 kOe. These results and the easy axis ordering of samples have been determined by energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, X-ray diffraction, and vibrating sample magnetometer analyses.     

脉冲准分子激光扫描沉积(PLD)高c轴取向V2O5/Si薄膜及结构分析

采用脉冲准分子激光大面积扫描沉积技术,在Si(111)单晶衬底上沉积了多晶V2O5薄膜,经300℃以上退火处理得到了具有高c-轴取向生长的V2O5膜。300℃以上热退火处理的薄膜表面具有正常的化学计量比（无氧缺位）,晶粒间界明显,晶粒呈针棒状,晶粒尺寸在100－200nm之间。采用X射线衍射（XRD）、Raman光谱（RS）、Fourier红外光谱（FT－IR）及透射电镜扫描附件（STEM）对沉积及不同温度下退火处理的样品进行了结构分析。研究结果表明：V2O5/Si薄膜经400℃热处理后表面部分处于低价态的钒离子已被氧化为V2O5。     

Growth behavior and thermally stable electrical properties of TiNbO5 nanosheet thin films grown using the electrophoretic method

TiNbO₅ (TNO) thin films were deposited by electrophoresis at room temperature by using TNO⁻ nanosheets. These TNO films exhibited a large (001) interplanar distance (1.18 nm) owing to the presence of TBA⁺ between the TNO layers. The TBA⁺, which were used to synthesize the TNO⁻ nanosheets, were removed from the TNO film after annealing at 600 °C. Two types of structures were developed in the film annealed at 600 °C: type-1 and type-2, which revealed (001) interplanar distances of 0.52 and 0.71 nm, respectively. The TNO film annealed at 600 °C showed a dielectric constant of 48.5, low dielectric loss (0.02), and small leakage current density of 4.16 × 10⁻⁷ A/cm² at 0.6 MV/cm. The dielectric properties were stable with respect to the film thickness and the applied electric field; the dielectric and insulation properties were maintained up to 300 °C. Therefore, TNO films are good candidates for high-temperature capacitors.     

Development of an electroless CoNiZnP solution for high coercivity films

This paper describes the development of an electrolessly deposited CoNiZnP film for use in magnetic storage devices. A low temperature type solution, which can be operated at 310 K, has been developed. High coercivity films, which have a coercivity of 135 kA m^–1 (1700 Oe) at a film thickness of 80 nm, are deposited from the solution     

NiZnCu Ferrite Thick Film with Nano Scale Crystallites Formed by the Aerosol Deposition Method

This paper describes the magnetic properties of NiZnCu ferrite film deposited at room temperature by an aerosol deposition method (ADM). The thickness of the film was 6 μm and the deposition rate was estimated as 2 μm/min. The microstructure of as-deposited at room temperature films consists of randomly oriented nanocrystallites with a size of 20 nm. As-deposited and annealed films exhibited the following magnetic properties: intensity of magnetization M _s= 0.147 T (117 emu/cm³), coercivity H _c= 40.58 kA/m (510 Oe); and M _s= 0.3 T (250 emu/cm³), H _c= 14.95 kA/m (188 Oe), respectively.