介质微结构与未来磁记录方式中记录过程的微磁学研究
发布时间：2018-12-29 07:58
【摘要】：在2004-2006年间，计算机硬盘中的数据记录方式逐渐由水平磁记录方式转向垂直磁记录方式。可是随着记录密度的进一步提高，垂直磁记录方式也在接近超顺磁性的限制，因此，对下一代磁记录方式的研究势在必行。能量辅助磁记录、比特图形磁记录和叠层瓦片式磁记录是记录密度有望超过1Tbit/in2的新型磁记录方式。这三种磁记录方式对介质的磁性参数和微结构的要求是各不相同的，相应的磁记录过程也有较大的差异。因此，在综合考虑介质的热稳定性、信噪比和可写入性的前提下，本文研究了比特图形磁记录和叠层瓦片式磁记录所采用的介质、记录过程及密度极限，同时还分析了能量辅助磁记录所使用的L10FePt介质中的孪晶结构对磁记录性能的影响。 本文首先从实验中观察到的纳米颗粒中的五重孪晶结构出发，建立了一个解析的模型来理解孪晶结构的存在对磁晶各向异性场的影响。计算结果表明，孪晶结构的存在会大幅降低颗粒的磁晶各向异性场，，同时造成磁晶各向异性场的分布，这会降低介质的热稳定性，增大反转场的分布宽度，降低信噪比。这个问题的研究对理解磁晶各向异性场的分布有普遍的意义。 使用双颗粒模型对交换耦合（ECC）介质的反转特性进行了研究，分析了介质磁性参数与反转场的关系，为设计热稳定性和可写入性都良好的ECC介质提供了指导。随后，分别对垂直薄膜介质和ECC介质进行了叠层瓦片式磁记录过程的模拟，统计了不同记录密度下的信噪比，发现ECC介质具有更高的信噪比和密度极限，同时还对ECC介质的磁性参数作了进一步的优化。 在对光刻法制备的比特图形介质（BPM）的磁记录过程的模拟中，研究了实现写入同步的时间窗口和对磁道偏移量的容忍度，发现降低由介质非均匀性造成的磁晶各向异性场的涨落有利于比特的正确写入。在对离子辐照法制备的BPM介质的磁记录模拟过程中发现，大幅降低比特之间被辐照区域的磁性质、对各个比特进行磁性隔离是实现正确写入的关键。通过优化系统参数和磁性参数，对不同密度的BPM介质的磁记录结果进行分析，可以预测离子辐照法制备的BPM介质的记录密度极限大约是3.0Tbit/in~2。
[Abstract]:From 2004 to 2006, the data recording in computer hard disk gradually changed from horizontal magnetic recording to vertical magnetic recording. However, with the further improvement of recording density, the perpendicular magnetic recording is approaching the limit of superparamagnetism. Therefore, it is imperative to study the next generation magnetic recording. Energy assisted magnetic recording, bit pattern magnetic recording and laminated tile magnetic recording are new magnetic recording methods, which are expected to exceed 1Tbit/in2. The three kinds of magnetic recording methods have different requirements on the magnetic parameters and microstructure of the medium, and the corresponding magnetic recording processes are different. Therefore, on the premise of considering the thermal stability, signal-to-noise ratio and writeability of the medium, the recording process and the density limit used in the bit pattern magnetic recording and laminated tile magnetic recording are studied in this paper. The effect of twin structure in L10FePt medium used in energy-assisted magnetic recording on the magnetic recording performance is also analyzed. Based on the quintuple twin structure observed in the experiment, an analytical model is established to understand the influence of the twin structure on the magnetocrystalline anisotropy field. The results show that the existence of twin structure can greatly reduce the magnetocrystalline anisotropy field of particles and cause the distribution of magnetocrystalline anisotropy field, which will reduce the thermal stability of the medium, increase the distribution width of the inversion field and reduce the signal-to-noise ratio (SNR). The study of this problem is of general significance for understanding the distribution of magnetocrystalline anisotropic fields. The inversion characteristics of the exchange-coupled (ECC) medium are studied by using a two-particle model. The relationship between the magnetic parameters of the medium and the inversion field is analyzed, which provides guidance for the design of the ECC medium with good thermal stability and writeability. Then, the vertical thin film medium and ECC medium are simulated by laminated tile magnetic recording process, and the SNR of ECC medium under different recording densities is calculated. It is found that ECC medium has higher SNR and density limit. At the same time, the magnetic parameters of ECC medium are further optimized. In the simulation of the magnetic recording process of bit graphics medium (BPM) prepared by photolithography, the time window of writing synchronization and tolerance to track offset are studied. It is found that decreasing the fluctuation of magnetocrystalline anisotropic field caused by medium inhomogeneity is beneficial to the correct writing of bits. In the process of magnetic recording simulation of BPM prepared by ion irradiation, it is found that the key to correct writing is to greatly reduce the magnetic properties of irradiated regions between bits and to isolate the magnetic properties of each bit. By optimizing the system parameters and magnetic parameters, the magnetic recording results of BPM medium with different densities are analyzed. It can be predicted that the limit of recording density of BPM medium prepared by ion irradiation is about 3.0 Tbit / n ~ (2).
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TP333
本文编号：2394546
[Abstract]:From 2004 to 2006, the data recording in computer hard disk gradually changed from horizontal magnetic recording to vertical magnetic recording. However, with the further improvement of recording density, the perpendicular magnetic recording is approaching the limit of superparamagnetism. Therefore, it is imperative to study the next generation magnetic recording. Energy assisted magnetic recording, bit pattern magnetic recording and laminated tile magnetic recording are new magnetic recording methods, which are expected to exceed 1Tbit/in2. The three kinds of magnetic recording methods have different requirements on the magnetic parameters and microstructure of the medium, and the corresponding magnetic recording processes are different. Therefore, on the premise of considering the thermal stability, signal-to-noise ratio and writeability of the medium, the recording process and the density limit used in the bit pattern magnetic recording and laminated tile magnetic recording are studied in this paper. The effect of twin structure in L10FePt medium used in energy-assisted magnetic recording on the magnetic recording performance is also analyzed. Based on the quintuple twin structure observed in the experiment, an analytical model is established to understand the influence of the twin structure on the magnetocrystalline anisotropy field. The results show that the existence of twin structure can greatly reduce the magnetocrystalline anisotropy field of particles and cause the distribution of magnetocrystalline anisotropy field, which will reduce the thermal stability of the medium, increase the distribution width of the inversion field and reduce the signal-to-noise ratio (SNR). The study of this problem is of general significance for understanding the distribution of magnetocrystalline anisotropic fields. The inversion characteristics of the exchange-coupled (ECC) medium are studied by using a two-particle model. The relationship between the magnetic parameters of the medium and the inversion field is analyzed, which provides guidance for the design of the ECC medium with good thermal stability and writeability. Then, the vertical thin film medium and ECC medium are simulated by laminated tile magnetic recording process, and the SNR of ECC medium under different recording densities is calculated. It is found that ECC medium has higher SNR and density limit. At the same time, the magnetic parameters of ECC medium are further optimized. In the simulation of the magnetic recording process of bit graphics medium (BPM) prepared by photolithography, the time window of writing synchronization and tolerance to track offset are studied. It is found that decreasing the fluctuation of magnetocrystalline anisotropic field caused by medium inhomogeneity is beneficial to the correct writing of bits. In the process of magnetic recording simulation of BPM prepared by ion irradiation, it is found that the key to correct writing is to greatly reduce the magnetic properties of irradiated regions between bits and to isolate the magnetic properties of each bit. By optimizing the system parameters and magnetic parameters, the magnetic recording results of BPM medium with different densities are analyzed. It can be predicted that the limit of recording density of BPM medium prepared by ion irradiation is about 3.0 Tbit / n ~ (2).
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TP333
【共引文献】
相关期刊论文 前1条
1 张邦维;;未来数据储存技术与硬盘的发展(续)[J];微纳电子技术;2007年11期
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2 李rc;氧化铝模板自还原法制备金属及合金纳米线的表征与应用[D];中国科学技术大学;2013年
相关硕士学位论文 前4条
1 刘杰;图案化介质记录性能的微磁学仿真研究[D];华中科技大学;2012年
2 刘静;FePt和FePt-Si-N磁记录薄膜的制备、结构与性能[D];华南理工大学;2013年
3 陈漪;工作状态下TFC磁头热变形对飞行高度的影响研究[D];哈尔滨工业大学;2013年
4 王哲;电场对3d过渡金属及其合金薄膜磁晶各向异性能的调控[D];湘潭大学;2013年
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