Electronic structures of compounds related to iron-based superconductor BaFe2As2

• Main Author: 王瑞騰
• Other Authors: 楊志開
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/54077571125231480505

碩士 === 國立政治大學 === 應用物理研究所 === 100 === In recent years, besides the traditional copper oxide superconductors, Iron-based superconductors and higher critical temperature materials have become a new trend in research of high Tc superconductors . As the traditional copper oxide superconductors are still lacking a perfect theorem to explain how they work, and the higher critical temperature materials in different outer pressures or in the situation of doping have the problem of Tc increase, the research of Iron-based superconductors is therefore considered to be more potential. Instead of experimental analysis, this thesis applies the first principle calculation software – Vasp to analyze the electron properties. The main discussions are broken down into three significant parts with conclusions as follows: Part I is the discussion on the electron properties of FeS, FeSe and FeTe, such as density of state, band structure and Fermi Surface, and the change of the lattice constant of FeSe. Part II is the discussion on the doping effect. I choose Ba(Fe1-xRux)2As2 , that is, we substitute Ru for Fe by different X. By considering different types of spin polarize and different places where Ru doped in Ba(Fe1-xRux)2As2 crystal. The doping of Ru shows a property of the suppression of the magnetic moment. Ru atoms like to remain nonmagnetic in this structure. We consider two circumstances, X = 0.125 and X = 0.25. By using the first principle calculation method, we are trying to figure out how the suppression works. Part III--- we consider Ba(Fe1-xRux)2(As1-yPy)2 . By replacing Ru and P at the same time, we find that the P substations also decrease the magnetic moment of the nearest iron atoms. We consider X = 0.125 and 0.25，Y = 0.125 and 0.25.