Study On Magnetic,Half-metallic And Mechanical Properties Of Half-heusler FeMnY (Y=N,P,As) And CoMnY (Y=C,Si,Ge,Sn) Alloys

Recently,the rapid development of information technology requires the excellent spin-tronics functional materials.The investigation reveals that,as a well-order crystal structure,Heusler alloys exhibit many excellent properties as well as physical effects.Therefore,the researchers have performed many computational and experimental studies on Heusler alloys,in order to seek materials with unique application value.They hope to contribute to the development of information technology.By means of the first-principle method based on density functional theory,this dissertation adopts the Castep modules of Materials Studio software.The crystal structure,magnetic properties,half-metallic properties and mechanical properties of the half-Heusler alloys FeMnY(Y=N,P,As)and CoMnY(Y=C,Si,Ge,Sn)have been investigated in details.The research results are as follows:1.Structural optimization of FeMnY(Y=N,P,As)shows,the minimum energy are determined as-7150.36(1)e V,-6799.35(3)e V and-676767.27(2)e V,respectively.The equilibrium lattice constant values are determined as 5.03(0)?,5.31(5)?and5.49(8)?,respectively.Investigation reveals that,when the Fe atom is at(0,0,0),the alloys can become stable.The FeMnP and FeMnAs alloys are both determined as half-metal materials.The total magnetic moment of the two materials is close to 2?.According to Slater-Pauling rule M_t=Z_t-18,we can see that FeMnP and FeMnAs are both half-metal materials due to meet this rule.The FeMnN alloy is ordinary ferrous magnet.Mechanic properties shows the FeMnP,FeMnAs alloys display good ductility,while the FeMnN one doesn't meet the mechanical stable criteria.2.The lowest energy states of the ternary half-Heusler alloys CoMnY(Y=C,Si,Ge,Sn)have been computed.The equilibrium lattice constant values are determined as 5.03(0)?,5.41(1)?,5.52(5)?and 5.91(2)?,respectively.The density of states near the Fermi surface of the CoMnY(Y=C,Si,Ge,Sn)alloys mainly originate from the splitting hybridization of 3d electrons of the Co andMnatoms.The analysis of band structures and density of states reveals,the CoMnY(Y=C,Si,Ge)alloys belong to half-metallic materials,while CoMnSn ordinary magnetic materials.Moreover,the calculation of mechanical properties shows that the CoMnY(Y=Si,Ge,Sn)alloys exhibit easily extensible and anisotropic,while the CoMnC alloy does not meet the mechanical stability.