中心孔探测磁超分辨耦合薄膜制备及性能研究
文献类型：学位论文
| 作者 | 方铭 |
| 学位类别 | 博士 |
| 答辩日期 | 2005 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 干福熹 |
| 关键词 | 磁光存储 轻稀土掺杂 中心孔磁超分辨读出技术 交换耦合双层薄膜 SbOx薄膜 |
| 其他题名 | Study on the preparation and properties of the coupled films for CAD-MSR |
| 中文摘要 | 本文的主要内容包括以下几个方面的研究工作：非化学计量比氧化物Sbox薄膜的结构、结晶动力学、光学和短波长光存储特性研究；聚焦光斑克尔磁滞回线测试装置的搭建以及利用该装置对磁光薄膜的热效应分析；掺杂轻稀土元素Nd对GdFeCo薄膜磁和磁光性能的影响；NdGdFeCo／TbFeC。交换祸合双层薄膜用于中心孔磁超分辨读出（CAD－MSR）时的磁和磁光性能。首先较全面地综述了磁光存储的读写原理和特点，着重介绍了几种磁光存储材料和高密度数字磁光存储技术的研究现状和发展趋势，并概述了一些非化学计量比氧化物薄膜用作光存储材料的研究现状，提出了本论文研究的具体内容。对不同氧分压下溅射制备的Sbox薄膜的结构、结晶动力学、光学和短波长光存储特性研究表明：沉积态Sbox薄膜是非晶态，经过退火处理后发生了由非晶态向晶态的相变；P伪中Ai为7％时，退火前后薄膜在400－60Onm范围内反射率对比度最大，在400、500、600nln处分别为20％、22％、18％，高的反射率对比度有利于获得高的载噪比；薄膜的结晶温度和结晶活化能随着溅射时氧分压与氢分压比的增加而增加；静态存储性能的测试结果表明，在Po2／PAr为7％，写入功率15mw、写入脉宽50Ons时，薄膜写入前后反射率对比度最大为犯％。Sbox薄膜可以用作短波长光存储材料。我们自己搭建的一套聚焦尤斑磁光克尔回线测量装置可以用来测试磁光薄膜的克尔回线，从测出的回线上可以求出薄膜的矫顽力Hc。我们采用了He-Ne！激光，其最大输出功率可达卜nw，因此可以在测试薄膜克尔回线的同时对l薄膜起到加热的作o通过调节激光器的输出功率，可以改令薄障的溟膺一11昌'一""，，"，，，代入翻声、1、勺卜月，丈日J丫且几z，之。仪"里．I不同功率激光照射下（即改变薄膜的温）薄膜的克尔回，并求出不同照射功！率下薄膜的矫顽力Hc，再通过计算照射激光功率与薄膜温度之间的关，可"得出薄膜的矫顽力Hc随薄膜温度的变化关系曲线。从这个Hc一T曲线上就可以求出薄膜的居里温度Tc和补偿温度Tcomp（如果存在的话）。通过直流磁控溅射法制备了不同含量的轻稀土Nd掺杂的NdGdFeCO薄膜，研究了NdGdFeCO薄膜的磁和磁光性能。结果表明在GdFeCO薄膜中掺入轻稀土Nd会引起薄膜补偿温度的下降，同时薄膜的居里温度基本保持不变；掺入Nd后薄膜在室温下的饱和磁化强度增加，同时薄膜的矫顽力下降。但是当Nd的掺入量超过一定值后，薄膜的饱和磁化强度不再继续增加，反而开始呈现出下降的趋势。通过测量不同Nd掺入量的薄膜在可见光范围内的克尔谱，发现在短波长范围（特别是在400nm左右），薄膜的克尔角明显随着Nd的掺入增大，有利于在短波长下记录和读出时获得较大的读出信号，因此可以提高存储密度。但是Nd的掺入量有一个最佳值（在我们的实验中为12％），超过这个值后会使克尔角降低，使磁光性能恶化，所以要严格控制轻稀土Nd的掺入量，一般情况下在12％左右为最佳。研究了NdGdFeCo／TbFeCo交换藕合双层薄膜的变温性能，发现随着温度的升高，读出层NdGdFeC。的磁化方向从平面磁化逐渐转变为垂直磁化，70℃到100℃温度范围内读出层磁化方向的转变速度较快，所制备的交换耦合两层薄膜适于作CAD-MSR记录介质。随温度变化，磁化方向的快速转变有利于获得更好的MSR性能。用微磁理论分析了不同温度下NdGdFeCo／TbFeCo交换祸合两层薄膜读出层表面的磁化方向彻习。发现读出层表面处的必角随着温度升高而减小，说明读出II层表面处的磁化方向逐渐由接近于平面磁化向接近于垂直磁化转变。因此，读出层的极向克尔角随着温度升高也将增大。此理论分析结果与实验结果是一致的。 |
| 英文摘要 | This dissertation's main topics focus on setting a kind of apparatus to test magneto-optical Kerr hysteresis loop irradiated by focused laser and its thermal effect on magneto-optical films, investigating the effects of doped Nd on magnetic-optical properties of GdFeCo thin film, analyzing magnetic and magneto-optical properties of exchange coupled double layer film (ECDL) NdGdFeCo/TbFeCo for center aperture detection magnetically induced super resolution (CAD-MSR), and studying on the structural, crystallization kinetics, optical and short-wavelength optical recording properties of non-stoichiometric SbOx thin films as well. Firstly, it reviewed the read/write principle and characteristic of magneto-optical recording. Secondly, it gave detailed and comprehensive overview on the current status and the developing trend of the magneto-optical recording materials and high-density digital magneto-optical recording technology. Thirdly, it did an overview on several non-stoichiometric oxides optical recording media. Finally, it put forward the research contents in more details. SbOx thin films were deposited by reactive dc sputtering using Sb target in a mixture of argon-oxygen system with different ratio of oxygen to argon. The structure, crystallization kinetics, optical and short-wavelength optical recording properties of the films were studied. It was found that the deposited SbOx thin films were amorphous state, which was crystallized after annealing. The films deposited at PO2/PAT of 7% had largest reflectivity contrast, which was 20% at 400 nm, 22% at 500 nm and 18% at 600 nm, respectively. The lager reflectivity contrast is in favor of attaining high carrier to noise ratio (CNR). The crystallization temperatures and activation energies of SbOx thin films increased with the ratio of oxygen to argon. According to the results of static test, for the films deposited under the condition of PO2/PAT of 7% the reflectivity contrast can be as high as 32% under the writing power 15 mW and writing pulse width 500 ns. SbOx thin film could be a candidate medium for blue-green short-wavelength high density optical storage. We can test the Kerr hysteresis loop of magneto-optical thin films using the self-made apparatus, and determine the coercive force of the films. The films were heated when we tested the Kerr hysteresis loop, because we used a He-Ne laser whose maximum output power could achieve 75 mW. So the temperature of films changed by adjusting laser power. By measuring the Kerr hysteresis loop and coercive force of the films irradiated by focused laser beam with different power, we obtained the relationship of film coercive force and film temperature by calculating temperature of the films irradiated by different power laser. Then the Cuire temperature Tc and compensation temperature Tcomp (if existed) of the films were worked out. NdGdFeCo thin films with different light rare Nd concentration were prepared by dc magnetron sputtering, and their magnetic and magneto-optical properties were investigated. The results indicated that Tcomp decreased as the Nd concentration increasing, but Tc remained almost unchanged and around 310°C. The saturation magnetization Ms at room temperature increased as Nd concentration increasing, meanwhile the coercive force decreased. When the Nd concentration exceeded a certain quantity, the saturation magnetization was not increased any more but began to decrease. The magneto-optical Kerr spectra of NdGdFeCo thin films were measured in visible light range, and the results showed that the Kerr rotation angle of films with around 400 nm increased with Nd concentration, which was propitious to gain large signal to enhance recording density at short wavelength recording and readout. The optimal Nd concentrationof 12% in our experiment was obtained. When exceeding the quantity, it could decrease Kerr rotation angle and deteriorate the magneto-optical properties of films. The magnetization transition caused by temperature was investigated. The results indicated that the magnetization orientation of the readout layer (NdGdFeCo) changed from in-plane to perpendicular direction with the rise of the temperature, and the change was faster in the range of temperature from 70 °C to 100°C. So the ECDL was suitable for CAD-MSR. The rapid change of the magnetization direction with temperature is important to obtain an excellent MSR performance. The profile of the magnetization direction ( |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15795]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 方铭. 中心孔探测磁超分辨耦合薄膜制备及性能研究[D]. 中国科学院上海光学精密机械研究所. 2005. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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