新型掺铈钇铁石榴石磁光薄膜材料

对新型掺铈钇铁石榴石磁光薄膜材料(Ce:YIG)的制备工艺、磁光特性及理论分析进行了较全面的评述,并指出今后研究的方向。     

Ce掺杂对TbFeCo材料磁光性能影响的研究

采用射频磁控溅射方法制备了TbFeCo非晶磁光薄膜，并在TbFeCo中引入轻稀土元素Ce，测试了薄膜的磁光性能。研究了薄膜成分对其磁光性能的影响。结果表明；在TbFeCo薄膜中掺入少量Ce时，薄膜的磁光克尔角及矫顽力都有所提高，矩形度也增加了。但随Ce掺入量的增加，薄膜的磁光性能发生恶化，较好的掺杂在10.31?左右。     

非晶稀土——过渡金属磁光薄膜热稳定性研究

采用射频磁控溅射方法制备非晶ＤｙＦｅＣｏ磁光薄膜。样品的克尔回线、转矩曲线的测试显示，薄膜具有优良的磁和磁光性能。退火研究表明，随着退火时间的增加，矫顽力下降，垂直磁各向异性能减少，但克尔角变化不明显，其内在机制与薄膜中的微缺陷和应力的弛豫过程有关。     

退火工艺对射频磁控溅射Bi:YIG薄膜磁性能的影响

对于用射频磁控溅射技术在Si基片上制备的Bi:YIG系薄膜,用快速循环退火方法对其进行晶化处理,研究了退火温度对Bi:YIG薄膜结晶状态和形貌的影响,以及退火气氛和循环周期对薄膜性能的影响.结果表明,用快速循环退火可以在si单晶基片上得到磁性能优良的薄膜(饱和磁化强度139 kA/m,矫顽力6.37 kA/m)并使薄膜形貌有较大改善,在石英基片上制备的薄膜法拉第角比常规退火的薄膜增大了约一倍.     

离子注入法增强YIG单晶薄膜的磁光效应

利用离子注入技术，将Ce^ 3离子注入到YIG单晶薄膜中，剂量为10^14-10^16ion/cm^2，能量为500keV。对注入前后的样品进行光吸收谱测量，发现注入后的样品光吸收有明显的增加，且样品颜色变深，对样品进行高温退火，可有效地降低光损耗，离子注入样品磁光特性测量表明Ce^ 3薄膜有很大的磁光增强作用，且法拉第旋转角随注入剂量增加而增大。     

用射频磁控溅射法在二氧化硅衬底上制备磁光Ce∶YIG薄膜

使用射频磁控溅射法在非晶态的二氧化硅衬底上制备Ce1YIG磁光薄膜。生成的Ce1YIG薄膜为非晶态形式 ,经过后续的热处理过程 ,转变为晶化薄膜 ,在用波长为 6 30nm的激光测量时 ,薄膜的饱和法拉弟旋转系数θF 为 80 0°/mm。晶化薄膜具有很强的平行于膜面的磁化强度 ,用VSM测得晶化薄膜的居里温度为 2 2 0℃。实验结果表明 :所制备的薄膜适宜于制备波导型磁光隔离器。同时 ,这一方法为进一步研究非互易平面光波回路打下了基础     

掺铋钇铁石榴石薄膜材料磁光性能的计算机辅助设计

从介电张量表达式出发,利用相应模型对微观表达式进行简化,得到了法拉第旋转角和光吸收系数的计算公式．进一步建立了描述Bi－YIG磁光性能的理论模型和参数数据库,在此基础上实现了Bi－YIG磁光性能的计算机辅助设计,其结果与实验符合得较好．     

RF溅射淀积Ce∶YIG磁光薄膜的热处理结晶化研究

基片温度低于溅射外延条件 ,采用低溅射功率密度磁控溅射沉积 ,进行后期热处理结晶化 ,制备出膜厚为 30 0 nm的掺铈钇铁石榴石 Ce∶ YIG磁光薄膜。对热处理前后的磁光特性进行比较 ,并分析了热处理结晶化过程中附属相的变化。薄膜在空气中热处理结晶化温度在 650℃附近。热处理后 ,室温下 633nm处其法拉第旋转系数约为 1.9× 10 4 deg/ cm,光吸收系数为 2 50 0 cm-1。     

界面对TbFeCo薄膜磁畴的形成和移动的影响

本文用振动样品磁强计和磁光克尔回线测试仪研究了非晶ＴｂＦｅＣｏ薄膜和ＡＩＮ薄膜之间的界面对非晶ＴｂＦｅＣｏ薄膜磁畴的形成和移动的影响，得出结论：ＡＩＮ薄膜的表面粗糙程度对非晶ＴｂＦｅＣｏ薄膜的磁和磁光性能有影响。当表面光滑时，非晶ＴｂＦｅＣｏ薄膜的磁滞回线和磁光克尔回线的矩形比高，这是由于磁畴的成核和移动与界面粗糙性质紧密相关的结果。     

石榴石型磁光存储材料

稀土铁石榴石薄膜被认为是最具应用前景的下一代磁光记录材料。稀土铁石榴石薄膜具有高的矫顽力、良好的热、化学稳定性及强的磁光效应等特点；特别是当Ｂｉ３＋和Ｃｅ３＋离子部分取代石榴石结构中的稀土离子后，可以极大地增强其磁光效应。本文就磁光记录的原理、磁光存储材料、稀土铁石榴石磁光薄膜的制备及其如何降低石榴石薄膜中的晶界噪声等问题作了一些探讨。     

Effect of deposition temperature on the properties of sputtered YIG films grown on quartz

Yttrium Iron Garnet (YIG), Y₃Fe₅O₁₂, is an oxide material that has potential applications in the magneto-optical recording media and microwave device industries. These materials, when synthesized in thin film form, usually require post-deposition annealing in order to enhance their physical properties. Furthermore, integration of YIG based optical components requires the synthesis of high quality YIG material on quartz, a process that may be problematic due to poor adhesion and lattice mismatch. Thus, we have conducted a study on the effect of deposition temperature (from 25 to 800 °C) and post-deposition annealing (at 740 °C) on the crystalline quality and chemical composition of YIG thin films, grown by radio-frequency magnetron sputtering, on quartz substrates. X-ray diffraction (XRD) shows that as-grown layers are amorphous, and subsequent annealing is necessary to induce film crystallization. Rutherford backscattering spectrometry analyses were also conducted and the chemical composition of the films was found to depend on initial deposition temperature and is affected by post-deposition anneals. Comparison of the XRD and RBS results point out to the existence of an optimal deposition temperature at about 700 °C for the formation of high crystalline quality and stoichiometric YIG thin films. Magnetic measurements were found to correlate to the XRD and RBS analyses.     

YIG rod ferrite limiter with extended dynamic range

Analytical and experimental results obtained on aC-band ferrite limiter which utilizes a YIG rod inserted down the center of a coupled dielectric resonator bandpass structure are described. This device is aimed at providing receiver protection for communication systems operating in a dense, high signal power environment. By utilizing a long thin single-crystal YIG rod instead of YIG spheres, the dynamic range has been extended from 20 dB to 35 dB. The threshold power varies from 5 dBm at 4.4 GHz to 15 dBm at 5 GHz with an insertion loss of less than 1 dB.     

Magneto-Optical Faraday Rotation in Ce:YIG Thin Films Incorporating Gold Nanoparticles

We report an experimental study on optical and magneto-optical properties of Ce-substituted yttrium iron garnet thin films incorporating gold nanoparticles. Au nanoparticles were formed by heating Au thin film on cubic quartz and garnet substrates in a vacuum chamber and a Ce:YIG layer was deposited on them by the aid of the pulsed laser deposition method. A large enhancement of the Faraday rotation was obtained in the sample with Au nanoparticles on a quartz substrate and the effect of the substrate material on improving the optical and magneto-optical response of samples were investigated.     

BST/YIG复合材料的相结构、介电性能和磁性能的研究

以铁电性的钛酸锶钡（BST）和铁磁性钇铁氧体（YIG）为原料,采用固相反应法,合成了一系列铁电/铁磁复合材料,并对铁电/铁磁复合材料（YIG/BST）的介电性能和磁性能进行了详细地研究. 结果表明：在一定温度下烧结所得的铁电/铁磁复合材料,由铁电相和铁磁相两相组成;xBST-(1-x)YIG(x=0,0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9,1.0)复合材料具有良好的介电性能和磁性能, 其介电常数实部ε′与虚部ε″均随BST含量的增加而升高,且介电常数的谐振峰随着YIG含量的增加而向频率高的方向移动.磁导率实部μ′与虚部μ″均随BST含量的增加而降低. 在YIG铁氧体中加入适量的陶瓷BST构成复合材料,可以有效地改善截止频率,提高高频电磁特性.     

The effect of SrTiO<Subscript>3</Subscript> addition on the magnetic and microwave properties of yttrium iron garnet

The effect of SrTiO₃ addition on the microstructure and magnetic properties of yttrium iron garnet prepared by a conventional ceramic method was investigated using scanning electron microscopy, X-ray diffractometry, vibrating sample magnetometry, and ferrimagnetic resonance experiments. A YIG specimen sintered at 1693 K with 0.2 mol% SrTiO₃ addition showed above 98% densification of theoretical density without changing in magnetic properties of YIG. A YIG specimen sintered at 1693 K with 0.2 mol% SrTiO₃ showed ferrimagnetic resonance linewidth ΔH of about 80 Oe.     

（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。     

Low-temperature synthesis and microstructure-property study of single-phase yttrium iron garnet (YIG) nanocrystals via a rapid chemical coprecipitation

Single-phase yttrium iron garnet (Y₃Fe₅O₁₂, YIG) nanocrystals have been synthesized via a rapid chemical coprecipitation process with reverse strike operations, followed by calcining the precipitates at the temperature around 750 °C. The formation of YIG nanocrystals from the amorphous precipitates and their microstructural features and magnetic properties were investigated by FT-IR, XRD, TG-DSC, FESEM, TEM and VSM. It has been found that the as-obtained precipitates could be thermally activated to directly form the crystalline phases of garnet structure around 650 °C, including cubic YIG and minor tetragonal YIG but no trace of YFeO₃, which was often involved during the synthesis of YIG or doped-YIG when a chemical coprecipitation method was used. The calcinations could make the tetragonal YIG entirely transform into the cubic phase at 750 °C and allow the crystallites of the latter to grow from ∼22 nm to ∼50 nm in size almost linearly as a function of the temperature ranging from 650 °C to 900 °C. Moreover, the room temperature saturation magnetization of the samples after calcinations at various temperatures showed a nonlinear increase from 0.24 emu g⁻¹ to 24.54 emu g⁻¹, which should be associated with the alignments of atomic magnetic moments in the materials from completely-disordered to partially-ordered firstly and further to completely-ordered and, in the last stage, mainly with the growing YIG nanocrystals.     

Liquid phase epitaxy and magneto-optical properties of garnet films for integrated optics

Films of different compositions have been obtained by liquid phase epitaxy on 〈111〉 GGG substrates; their magnetic and optical properties have been investigated at 1.152 μm in view of their future utilization in integrated optics. Conditions of growth and results of characterization are given for films of the following compositions: (Sc, Ga): YIG, (Ga,Ga):YIG, Bi:YIG, (Pr,Ga):YbIG and (Pr,Bi,Ga):YbIG.     

Electromagnetic excitation of ultrasonic oscillations by yttrium iron garnet films on gallium gadolinium garnet substrates

We have studied the phenomenon of contactless excitation of ultrasonic oscillations by thin yttrium iron garnet (YIG) films on gallium gadolinium garnet (GGG) substrates upon application of the superposition of a constant magnetic bias field and alternating magnetic field. Dimensional resonance effects that cannot be explained in the framework of existing theoretical notions have been discovered, in particular, in dependences of the amplitude of excited longitudinal oscillations on the YIG film thickness, frequency of ultrasound, and degree of homogeneity and strength of the magnetic bias field. It is suggested that the observed phenomenon is caused by resonant participation of the intrinsic oscillations of domain walls in the excitation of ultrasound.     

Growth of epitaxial substituted garnet films by hydrothermal synthesis

A new hydrothermal technique is described in which the garnet synthesis is performed directly in the autoclave in low concentration basic solutions (NaOH or KOH). This method avoids a strong attack of the substrate and leads to uniform thickness and composition films. The best experimental conditions are given for the growth of Ga:YIG, Gd:Ga:YIG, Eu:Ga:YIG, Eu:Ga:ErIG and Gd:Ga:ErIG films on GdGaG substrates. Magnetic characterizations are presented and the properties of hydrothermal garnet films are discussed and compared with those of L.P.E. and C.V.D. garnet films.