系列CoMnZnZ四元Heusler化合物的结构和半金属铁磁性  

Structure and half-metallic ferromagnetism of quaternary Heusler compounds CoMnZnZ

作　　者：许佳玲[1] 贾利云[1,2] 靳晓庆 郝兴楠 马丽[2] 侯登录[2] Xu Jia-Ling;Jia Li-Yun;Jin Xiao-Qing;Hao Xing-Nan;Ma Li;Hou Deng-Lu(Department of Mathematics and Physics,Hebei Instituteof Architecture Civil Engineering,Zhangjiakou 075000,China;College of Physics and Information Engineering,Hebei Normal University,Shijiazhuang 050024,China)

机构地区：[1]河北建筑工程学院数理系,张家口075000 [2]河北师范大学物理科学与信息工程学院,石家庄050024

出　　处：《物理学报》2019年第15期303-309,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11504247);河北省自然科学基金(批准号:A2018205144,E2016205268);河北省科技支撑计划项目(批准号:13211032,15211036);张家口市财政支持计划项目(批准号:1611070A);河北建筑工程学院博士基金资助的课题~~

摘　　要：通过第一原理计算理论预测了CoMnZnZ(Z=Si,Ge,Sn,Pb)系列Heusler合金的弹性常数、电子结构和磁性,并根据弹性常数计算得到弹性模量等参量,计算了该系列化合物声速和德拜温度.计算采用全势线性缀加平面波方法,交换相关函数采用基于Perdew-Burke-Ernzerhof的广义梯度近似泛函.弹性模量结果表明晶体呈现韧性特征;承受剪切的性能弱于承受单轴压缩的性能;结构组成具有较低的各向异性性能.电子结构的计算显示CoMnZnZ(Z=Si,Ge,Sn)三个化合物属于半金属铁磁体,但是CoMnZnPb化合物并不显示半金属特性.CoMnZnZ(Z=Si,Ge,Sn)三个化合物的磁矩通过Slater-Pauling法则进行计算得到的量值与第一原理计算得到的完全一致,遵从总的价电子数减去28的Slater-Pauling法则,三个化合物磁矩为整数且自旋极化率为100%.利用轨道杂化理论解释了此系列化合物半金属性的根源.Using the first principle full-potential linearized augmented wave method we study the electronic structure and elastic and magnetic properties of CoMnZnZ(Z=Si,Ge,Sn,Pb)LiMgPdSn-type Heusler alloys.These compounds have the composition CoMnZnZ with 1︰1︰1︰1 stoichiometry,where Z denotes the main group element Si,or Ge,or Sn,or Pb.The exchange-correlations are treated within the generalized gradient approximation of Perdewe-Burke-Ernzerhof.For each of all studied Heusler alloys,the ferromagnetic state is considered to be more stable than the paramagnetic state,judged by the energy.The total energy of the magnetic calculation is lower than that of the nonmagnetic state for each of all three serise compounds at the equilibrium lattice constant,indicating that the magnetic state is more stable than the nonmagnetic state.We determine the elastic constants C11,C12 and C44,which have not been established previously in experiment nor in theory.The elastic constant indicates the weakened resistance to sheardeformation compared with the resistance to unidirectional compression.We derive other mechanical parameters,i.e.,the shear modulus G,Young’s modulus E,Poisson’s ratio n,and shear anisotropic factor A,which are the important elastic moduli for applications.These compounds each have a lower anisotropy and possess a low probability to develop microcrack or structural defect in its growing process.The sound velocity and Debye temperature for each of the CoMnZnZ(Z=Si,Ge,Sn,Pb)compounds in their stable structure are calculated.The CoMnZnPb exhibits the lowest Debye temperature,and the highest value is observed for CoMnZnGe.The electronic structure calculations show that CoMnZnZ(Z=Si,Ge,Sn)each exhibit a gap in the band of minority states,and they are clearly half-metallic ferromagnets,except for the CoMnZnPb.The CoMnZnZ(Z=Si,Ge,Sn)compounds and their magnetic moments are in reasonable agreement with the Slater-Pauling rule,and they comply with a Slater-Pauling rule of Mt=Zt– 28,which indicates the half metallicity

关 键 词：Heusler化合物 半金属 第一性原理 电子结构 

分 类 号：O482.523[理学—固体物理]