Study Of Electronic And Magnetic Of Mn Based Perovskite Supercell From First Principles

The first-principle methods based on density functional theory gradually becomes a crucial research tool and it plays an important role in physics, chemistry and biology. The application of first-principle calculation method greatly facilitates the research of materials, which gives a theoretical prediction of finding functional materials. With the high-speed development of computer software and hardware, first-principle calculation method has become an efficient and cost-effective mean of research.Perovskite oxides are a class of common composite oxides. Their properties, especially the complex phase figure formed by doping, which contain piezoelectricity, superconductivity, magnetoresistance, catalysis, ion conductor, etc., have wide range of applications. The application area contains sensor, solid fuel battery, solid electrolyte, solid resistor, redox catalyst and so on. It is a hot topic of chemistry, physics and material science. It is very complex of the Mn based perovskite oxides' magnetic properties. Particularly, after doping is introduced, it shows many phenomena including charge-orbit order states, spin glass states, phase separation, etc.Mn based perovskite supercell, especially La2NiMnO6 and La2CoMnO6 are two high focused Mn based double perovskite oxides recently. They have potential application value. In this work, we investigate the electric structure, electric and magnetic properties of La2NiMnO6 and La2CoMnO6. In addition, we investigate the electric structure and electric property of the structures after doping Sr. The reason of the difference among different structures has discussed by means of calculating ferromagnetic and antiferromagnetic states of different atomic ordering structure.Our calculation confirms that La2NiMnO6 and La2CoMnO6 ferromagnetic states found in experiment are ground states and (111), (110) cation ordering states are ferromagnetic half-metal. For different doping of Sr, the energy calculation of quadrangle deformation shows that the impact of doping Sr can be ignored. The GGA calculation gives some half-metal states, while GGA+U calculation gives insulator states congruously. It reveals the effect of strong electronic correlations. Otherwise, with the introduction of p holes from doping Sr make the valences of Ni/Co and Mn change. It makes them different cation order and changes magnetic moment.