The Relationship Between The Superconductivity Of Doping MgB₂ And The Number Of Average Valence Electrons And The Study Of MgB₂ Thin Film's Metal-insulator Transitions

The work consists of two parts.The first part introduces the history of superconductivity,the basic properties of superconductivity and the classification of superconductor.It also reviews the studies on superconductivityin MgB₂ during the last few years,and discusses the close relationship between the interaction of the atom's valence electron and the superconductivity of doping MgB₂ system,for the recent discovery of superconductivity in MgB₂ at temperature as high as 39K has generated great interest in theoretical and experimental fields.The number of average valence electrons was used as an empirical criterion for the superconductivity of doping MgB₂.Through studying the number of average valence electrons(Zv)of the doping MgB₂ superconductor,it shows that the Zv of doping MgB₂ are mainly concentrated at 2.61.The second part presents the metal-insulation transition mechanism from the aspects of energy band theory,Anderson model,Mott metal-insulation transition model and Kondo effect and so on.We introduces the experiment on the fabrication of MgB₂ thin films of the Si/MgO substrates with RF magnetron sputtering method;the influence of different annealing temperature on films' properties was analyzed with X-ray diffraction pattern;the characteristic of resistance-temperature was studied with the method of direct current four probes.The results show that the correlation of electrons leads to metal-insulator transitions at 175.9K.The phenomenon was explained well with Mott model and Anderson model.Lastly sums up the research and put forwards suggestions for future study.