The Theory Of Magnetic Impurities Affect The Physical Properties Of The Copper-oxide High-temperature Superconductors

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 superconducting coherence peaks are strongly suppressed by the impurity. And with the increasing of the doping and the strength of the impurity the intensity of the zero-energy peak decreases and simultaneous splitting. Far away from the impurity, both the LDOS and the electron distribution show the same results as the uniform system.In chapterⅣ, using the Gutzwiller approximation theory and BdG equation, we discuss the effects of many magnetic impurities on the LDOS and the related physics properties within t-J-U model. We found that, far away from the impurity, both the LDOS and the electron distribution show the same results as the uniform system; while in the periphery near the impurity many magnetic impurities similar with single magnetic impurity because of impact of the impurities is localized. But in the center of the impurities the electronic local density of states becomes more complicated due to the interaction of multiple magnetic impurities.