t-J-U模型论文：磁性杂质对铜氧化物高温超导体物理性质影响的理论研究.docVIP

t-J-U模型论文：磁性杂质对铜氧化物高温超导体物理性质影响的理论研究 【中文摘要】杂质对铜氧化物高温超导材料物理性质的影响的研究是高温超导机理研究的热点之一。本文从t-J-U模型出发,利用Gutzwiller平均场近似和Bogoliubov-de Gennes(BdG)理论对铜氧化物高温超导材料中掺入的单个和多个磁性杂质对系统电子局域态密度及相关物理性质的影响进行了较为系统的研究。我们在第二章里简单介绍了可以有效描述Cu02平面内基本物理过程的t-J-U模型,并介绍了可以较好地处理电子强关联体系问题的Gutzwiller近似理论以及研究非均匀系统的BdG方程。我们在第三章里应用Gutzwiller近似理论和BdG方程讨论了单个磁性杂质对铜氧化物高温超导材料电子局域态密度的影响：从t-J-U模型出发讨论了在不同掺杂浓度时单个磁性杂质对系统电子局域态密度的影响和在最佳掺杂浓度时不同的磁性杂质势对系统电子局域态密度的影响。结果我们发现,随着掺杂浓度和磁性杂质势的不断增大,在磁性杂质附近,超导相干峰受到的抑制越来越强,并且由于磁性的增强,我们发现零能量附近的诱导峰逐渐变弱,同时发生劈裂。在远离杂质点处,电子局域态密度和电子分布等物理量依然保持均匀系统时的结果。在第四章我们应用Gutzwiller近似理论和BdG方程讨论了四个磁性杂质对铜氧化物高温超导材料电子局域态密度及相关物理性质的影响。我们发现,在远离杂质点,电子局域态密度和电子分布等物理量依然保持均匀系统时的结果；而在杂质点外围附近,由于杂质的影响是局域的,所以一般情况下,多个杂质存在时的情形和单个磁性杂质存在时相似。但是在多个杂质之间的格点,由于受到多个磁性杂质的相互作用,所以电子局域态密度变得更加复杂。 【英文摘要】The study of the effects of magnetic impurities in copper oxide materials is one of the hotspot issues to understand the mechanism of the high Tc materials. In this paper, within the t-J-U model and the Gutzwiller approximation, the effects on the local density of states of single and many magnetic impurities in copper oxide materials are studied systemically using the BdG equation.The paper is organized as follows. In chapterⅡ, a brief review about the t-J-U model, the Gutzwiller approximation theory and the BdG equation is given. It is believed that the essential low-energy physics of copper oxide materials can be described effectively by the t-J-U model, while the electronic correlation is treated properly within the Gutzwiller approximation theory.In chapterⅢ, within t-J-U model we study the effect of single magnetic impurity in the copper oxide materials using the Gutzwiller approximation theory and BdG equation, especially the effect on the local density of state (LDOS). We find that with the increasing of the doping and the strength of the impurity, the impurity have a great effect on both the LDOS and the electron distribution:around the magnetic impurity, a zero-energy peak is induced by the impurity, at the same time the su