Theoretical Study Of Magnetic Ordering In Hole-Doped Iron-Pnictides Superconductors

Iron based superconductors are an important research direction for studying high-temperature superconductors and even superconducting phenomena.As the second type of high-temperature superconductors since the discovery of cuprates,the phase diagram of iron-based superconductors is very similar to that of cuprates.As the concentration of electron or hole doping increases,the magnetic order transition temperature of both types of superconductors will decrease,and the superconducting term will gradually appear.The close connection between magnetism and superconductivity in the phase diagrams of two types of high-temperature superconductors reflects the significant importance of studying the magnetism of high-temperature superconductors.Among hole doped iron based superconductors,more abundant magnetic order states,which further reflects the importance of magnetic research on superconductivity research.This article theoretically calculates the different magnetic ordered states in hole doped iron based superconductors using the mean field theory.The specific content of the paper is as follows:1.The development history of superconductors is briefly introduced,the phase diagram,crystal structure and electronic structure of iron based superconductors are summarized.2.A detailed introduction was given to the magnetic ordering phenomenon and nematic states in hole doped iron-pnictides,with a focus overview on exploring their experimental and theoretical comparisons,in order to gain a deeper understanding of the impact of magnetic ordering and nematic state research on the overall research of iron based superconductors.3.Established a five orbit Hubbard model that conforms to the characteristics of iron based superconductors and an average field Hamiltonian containing various average field order parameters.The corresponding mean field wave function is obtained by solving the mean field Hamiltonian.Thus laying a theoretical foundation for subsequent programming and program calculation.4.It is proposed that there are magnetic ordered states in hole doped iron-pnictide superconductors,such as staggered tetramers withQ_tet=（?,?/4）,staggered trimers withQ_tri=（?,?/3）,and staggered dimers with Q_{di m}=（?,?/2）.Through the program calculation of the mean field,the results of the energy changes of each magnetic order term as the doping concentration increases were obtained.The results show that there is strong competition between different magnetic order states in the system;And during the calculation process,it was found that the evolution process of the above magnetic ordered states naturally includes the reversal of the anisotropy of the resistance.Our calculation results well explain the phenomenon found in the experiment that the magnetic order transition temperature decreases with the increase of hole doping concentration;And for the problem of anisotropic inversion of resistance found in experiments,a practical and reliable explanation is also provided through the results of anisotropic inversion of electron kinetic energy.