Heusler合金Co_2V_xMn_(1-x)Al的电子结构、磁性及半金属性

Electronic Structure,Magnetic Property and Half-Metallic Property of Heusler Alloy Co_2V_xMn_(1-x)Al

采用基于密度泛函理论(density functional theory,DFT)的缀加平面波方法,使用广义梯度近似(generalized gradient approximation,GGA)对Heusler合金Co_2V_xMn_(1-x)Al(x=0,0.25,0.5,0.75,1)的磁性、半金属性及电子结构进行了研究,揭示了晶格常数、总磁矩及费米能级随合金成分变化的规律,讨论了原子间相互作用对能隙的影响.研究发现,随着x的增加,系列合金的晶格常数呈线性增加,满足维加德定律(Vegard’s law);系列合金的总磁矩呈线性下降趋势,符合S-P规则(Slater-Pauling rule).随着x的增加,费米能级逐渐从Co_2MnAl的价带顶移动至Co_2VAl的导带底.当x=0.5时,费米能级恰好处于能隙中部且合金的形成热最低,此时合金具有最佳的半金属稳定性.结果表明四元合金有可能成为具有更高自旋极化率和更强抗干扰能力的自旋电子学材料.

Based on the density functional theory（DFT）,the electronic structure,magnetic properties and halfmetallicity of Heusler alloy Co_2V_xMn_（1-x）Al（x=0,0.25,0.5,0.75,1）are investigated via generalized gradient approximation（GGA）.It is found that the lattice constant of the alloys linearly increases and the total magnetic moment linearly decreases with the increasing of V content,following the Vegard＇s law and Slater-Pauling behavior very well,respectively.Furthermore,the Fermi level gradually moves from the valence band maximum to the conduction band minimum with the increasing of x.The Fermi level nearly locates in the middle of energy gap as x=0.5,suggesting excellent half-metallicity.The investigation of the formation energies of the alloys finds that the formation energy is the lowest as x=0.5,indicating Co_2V_（0.5）Mn_（0.5）Al has good stability as well.Quarternary Heusler alloy is a promising half-metallic candidate for spintronics applications.