基于Monte Carlo方法的磁性多层膜的物性研究
发布时间：2019-04-02 15:37
【摘要】：随着科学技术的发展,层状磁性材料的研究与发展备受关注。其中,亚铁磁材料中存在补偿温度,而补偿温度在磁记录方面有着重要的应用。同时,合成薄膜材料的技术和手段多样化,如脉冲激光沉积法、溶胶-凝胶法、金属-有机物气相沉积法、磁控溅射技术等,加上理论方面的突破与科学的实际运用,磁性多层膜材料正进入一个发展高潮期。针对层状混自旋磁性材料,建立了亚铁磁双层混自旋(1/2,1)的Ising模型、亚铁磁三层混自旋(1/2,1,3/2)的Ising模型和铁磁三层混自旋(1/2,1,3/2)的Ising模型。利用Monte Carlo方法,系统地研究了亚铁磁和铁磁Ising系统的磁性质和热力学性质,分析和讨论了温度、交换耦合作用、薄膜层厚和磁性原子浓度对系统的磁矩、磁化率、内能、比热、补偿行为和相变行为的影响。研究了亚铁磁双层混自旋(1/2,1)的Ising模型系统的交换耦合作用、层厚对系统磁性质和热力学性质的影响。结果表明,层内交换耦合Jbb增加时,系统的相变温度和补偿温度都在增加,发现Jbb越小,补偿行为越容易出现。温度与交换耦合作用的竞争,导致了磁矩曲线类型出现了Néel理论所预言的N型、Q型和P型曲线。层间交换耦合作用Jab的增加,对于相变温度和补偿温度,几乎没有影响。随着层厚L的增大,相变温度先升高后不变,在L较小时,补偿温度变化明显。研究了亚铁磁三层混自旋(1/2,1,3/2)的Ising模型系统的交换耦合作用、层厚和系统原子浓度对系统磁性质和热力学性质的影响,重点研究了系统的补偿行为和相变行为。研究结果表明:随着Jbb的增加,补偿温度没有影响,相变温度增大。Jcc越大,补偿温度越难出现。随着系统层厚L的增大,补偿温度不变,而相变温度增加。子格层厚Lb增加,相变温度增大,补偿温度消失,说明Lb越大,补偿温度越难出现。子格层厚Lc增加时,相变温度不变,补偿温度先增加后不变。改变系统原子浓度P,在相图中发现,系统出现了双补偿点。为了与相关有效场(EFT)的理论结果进行比较,对铁磁三层混自旋(1/2,1,3/2)Ising模型系统的相变行为进行了研究,获得了与EFT相符的结果。此外,当增大参数L、Lc和Jcc,系统的相变温度随着L、Lc和Jcc的增大而增大。当增大Lb和Jbb时,系统的相变温度几乎没有发生变化。
[Abstract]:With the development of science and technology, the research and development of layered magnetic materials have attracted much attention. Among them, there is compensation temperature in ferromagnetic materials, and compensation temperature has important application in magnetic recording. At the same time, the technology and means of synthesizing thin film materials are diversified, such as pulsed laser deposition, sol-gel, metal-organic vapor deposition, magnetron sputtering, etc., together with the breakthrough in theory and the practical application of science. Magnetic multilayer materials are entering a period of high tide development. For layered mixed spin materials, the Ising model of ferromagnetic double-layer mixed spin (1 ~ 2, 1), the Ising model of ferromagnetic three-layer mixed spin (1 ~ 2, 1, 3 ~ 2) and the Ising model of ferromagnetic three-layer mixed spin (1 ~ 2, 1, 3 ~ 2) have been established. The magnetic properties and thermodynamic properties of ferromagnetic and ferromagnetic Ising system are systematically studied by means of Monte Carlo method. The magnetic moment, magnetic susceptibility, internal energy and specific heat of the system are analyzed and discussed in terms of temperature, exchange coupling, thin film thickness and magnetic atomic concentration. The influence of compensation behavior and phase transition behavior. The exchange coupling effect and the effect of layer thickness on the magnetic and thermodynamic properties of the Ising model system with ferromagnetic bilayer spin (1 ~ 2, 1) have been studied. The results show that the phase transition temperature and compensation temperature of the system increase with the increase of intralayer exchange coupled Jbb. It is found that the smaller the Jbb is, the more likely the compensation behavior is. The competition between temperature and exchange coupling leads to the appearance of N, Q and P curves predicted by N 茅 el's theory. The increase of interlayer exchange coupling (Jab) has little effect on phase transition temperature and compensation temperature. With the increase of layer thickness, the phase transition temperature increases first and then does not change, and when L is small, the compensation temperature changes obviously. The exchange coupling of the Ising model system with three layers of ferromagnetic spin (1 ~ 2, 1, 3 ~ 2) is studied. The effects of layer thickness and atomic concentration on the magnetic and thermodynamic properties of the system are studied. The compensation behavior and phase transition behavior of the system are mainly studied. The results show that with the increase of Jbb, the compensation temperature has no effect, but the phase transition temperature increases. The larger the JCC, the more difficult the compensation temperature is. With the increase of layer thickness L, the compensation temperature does not change, but the phase transition temperature increases. The subgrid thickness Lb increases, the phase transition temperature increases, and the compensation temperature disappears, indicating that the larger the Lb is, the more difficult the compensation temperature will be. When the subgrid thickness Lc increases, the phase transition temperature does not change, and the compensation temperature increases first and then the compensation temperature does not change. Changing the atomic concentration P of the system, it is found in the phase diagram that there is a double compensation point in the system. In order to compare with the theoretical results of the correlation effective field (EFT), the phase transition behavior of the ferromagnetic three-layer mixed spin (1? 2, 1, 3? 2) Ising model is studied, and the results are in agreement with those of EFT. In addition, when the parameter L is increased, the phase transition temperature of LC and Jcc, systems increases with the increase of L, LC and Jcc. When Lb and Jbb are increased, the phase transition temperature of the system is almost unchanged.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O469
本文编号：2452675
[Abstract]:With the development of science and technology, the research and development of layered magnetic materials have attracted much attention. Among them, there is compensation temperature in ferromagnetic materials, and compensation temperature has important application in magnetic recording. At the same time, the technology and means of synthesizing thin film materials are diversified, such as pulsed laser deposition, sol-gel, metal-organic vapor deposition, magnetron sputtering, etc., together with the breakthrough in theory and the practical application of science. Magnetic multilayer materials are entering a period of high tide development. For layered mixed spin materials, the Ising model of ferromagnetic double-layer mixed spin (1 ~ 2, 1), the Ising model of ferromagnetic three-layer mixed spin (1 ~ 2, 1, 3 ~ 2) and the Ising model of ferromagnetic three-layer mixed spin (1 ~ 2, 1, 3 ~ 2) have been established. The magnetic properties and thermodynamic properties of ferromagnetic and ferromagnetic Ising system are systematically studied by means of Monte Carlo method. The magnetic moment, magnetic susceptibility, internal energy and specific heat of the system are analyzed and discussed in terms of temperature, exchange coupling, thin film thickness and magnetic atomic concentration. The influence of compensation behavior and phase transition behavior. The exchange coupling effect and the effect of layer thickness on the magnetic and thermodynamic properties of the Ising model system with ferromagnetic bilayer spin (1 ~ 2, 1) have been studied. The results show that the phase transition temperature and compensation temperature of the system increase with the increase of intralayer exchange coupled Jbb. It is found that the smaller the Jbb is, the more likely the compensation behavior is. The competition between temperature and exchange coupling leads to the appearance of N, Q and P curves predicted by N 茅 el's theory. The increase of interlayer exchange coupling (Jab) has little effect on phase transition temperature and compensation temperature. With the increase of layer thickness, the phase transition temperature increases first and then does not change, and when L is small, the compensation temperature changes obviously. The exchange coupling of the Ising model system with three layers of ferromagnetic spin (1 ~ 2, 1, 3 ~ 2) is studied. The effects of layer thickness and atomic concentration on the magnetic and thermodynamic properties of the system are studied. The compensation behavior and phase transition behavior of the system are mainly studied. The results show that with the increase of Jbb, the compensation temperature has no effect, but the phase transition temperature increases. The larger the JCC, the more difficult the compensation temperature is. With the increase of layer thickness L, the compensation temperature does not change, but the phase transition temperature increases. The subgrid thickness Lb increases, the phase transition temperature increases, and the compensation temperature disappears, indicating that the larger the Lb is, the more difficult the compensation temperature will be. When the subgrid thickness Lc increases, the phase transition temperature does not change, and the compensation temperature increases first and then the compensation temperature does not change. Changing the atomic concentration P of the system, it is found in the phase diagram that there is a double compensation point in the system. In order to compare with the theoretical results of the correlation effective field (EFT), the phase transition behavior of the ferromagnetic three-layer mixed spin (1? 2, 1, 3? 2) Ising model is studied, and the results are in agreement with those of EFT. In addition, when the parameter L is increased, the phase transition temperature of LC and Jcc, systems increases with the increase of L, LC and Jcc. When Lb and Jbb are increased, the phase transition temperature of the system is almost unchanged.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O469
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