| Recently,Chinese economy is in a period of rapid development.In addition,both high-technology information R&D and industrial produce require the research of new functional materials.Traditional microelectronics marked by semiconductors has been trapped in the bottleneck of geometric scale,and it is imperative to vigorously develop new functional materials.Therefore,spintronics,which takes into account the charge and spin properties of electrons,has emerged,which will greatly increase the processing speed and storage of information.Among them,the half-metal magnetic material has unique advantages in spin electrons.This material exhibits different properties in the both spin channels.That is,it has both semiconducting and metallic properties,resulting in a theoretical spin polarization rate of 100%.These properties make half-metal magnetic materials have unique scientific research and application value.Some binary compounds without transition metals have been reported as half-metal ferromagnets,which has aroused many researchers'interest.These metallic compounds contain no magnetic atoms,but exhibit magnetic and half-metallic properties.Alkali(alkaline earth)binary metal compounds are in this category,so the purpose of this paper is to find new half-metal materials without transition metals.By means of first-principles calculation method and the CASTEP module of the Material studio software,the research materials are simulated.The magnetic,half-metallic and mechanical properties of alkali earth compounds XC(X=Mg,Ca,Sr,Ba)and the alkali metals XSe(X=K,Rb,Cs)with RS,Zb and Cscl structures have been investigated.The relevant results are as follows:(1)The alkali earth compounds XC were optimized by the CASTEP module.The equilibrium states were obtained on the condition of RS?ZB?Cs Cl structures and spin-up states.The lattice constants of equilibrium state are 4.665?and 5.284?,and the total magnetic moments are 0.94?_B and 1.98?_B,respectively.The magnetic properties and mechanical properties of XC(X=Mg,Ca,Sr,Ba)were calculated based on these results.The study shows that Ca C is nearly half-metallic material,while Sr C and Ba C materials have the half-metallics.The analysis is that,the magnetic moment of the compounds formed by alkaline earth metal and C atom is firstly contributed by the energy level splitting of the P orbital of C atom,while the magnetic contribution of alkaline earth metal atom is few.By calculating the mechanical properties of XC compounds,it is found that Ca C and Ba C are anisotropic materials with good ductility.(2)The crystal models of XSe(X=K,Rb,CS)are analyzed,and it is determined that XSe is the most stable in Cs Cl structure.The lattice constants of equilibrium state calculated by KSe,Rb Se and CsSe are 3.894?,4.102?and 4.306?,and the total magnetic moments are 0.88?_B and 1?_B,1?_B,respectively.Based on this,the magnetic properties and mechanical properties of XSe(X=K,Rb,Cs)were calculated based on these results.The study shows that KSe is nearly half-metallic material,Rb Se and CsSe are half-metallic materials and both have magnetic.Through the analysis of the magnetic moment of each atom and the fractal wave density diagram,it is concluded that the magnetic moment of the compound formed by alkali metal and Se atom is mainly contributed by the energy level splitting of the p orbital of Se atom,while the contribution of alkali metal atom is very small.By calculating the mechanical properties of XSe compound,it is found that CsSe are one kinds of anisotropic materials with good ductility,while KSe and RbSe don't meet the mechanic stable law. |
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