第一性原理研究semi-Heusler合金CoCrTe和CoCrSb的半金属性和磁性  

First-principle studies of half-metallicities and magnetisms of the semi-Heusler alloys CoCrTe and CoCrSb

作　　者：姚仲瑜[1] 孙丽[1] 潘孟美[1] 孙书娟[1] 

机构地区：[1]海南师范大学物理与电子工程学院,海口571158

出　　处：《物理学报》2016年第12期258-266,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11364014;11364015);海南省自然科学基金(批准号:113005;20165196)资助的课题~~

摘　　要：采用第一性原理的全势能线性缀加平面波方法,对semi-Heusler合金CoCrTe和CoCrSb的电子结构进行自旋极化计算.CoCrTe和CoCrSb处于平衡晶格常数时是半金属性铁磁体,其半金属隙分别为0.28和0.22 eV,晶胞总磁矩为3.00μB和2.00μB.CoCrTe和CoCrSb的晶胞总磁矩主要来自于Cr原子磁矩.Co,Te和Sb的原子磁矩较小,它们的磁矩方向与Cr原子的磁矩方向相反.使晶格常数在±13%的范围内变化(相对于平衡晶格常数),并计算CoCrTe和CoCrSb的电子结构.计算研究表明,CoCrTe和CoCrSb的晶格常数变化分别在-11.4%—9.0%和-11.2%—2.0%时仍具有半金属性,并且它们晶胞总磁矩稳定于3.00μB和2.00μB.Half-metallic ferromagnet, in which the electrons with one spin band are metallic and the electrons with another spin band are semiconducting, is believed to be the most promising spin-injector material for spintronic devices, such as spin valves, spin filters, spin diodes, and magnetic tunnel junctions. The main advantages of half-metallic Heusler alloy over other half-metallic systems are their relatively high Curie temperatures and structural similarity to important binary semiconductors that are widely utilized in the industry. Thus far, half-metallicity has been predicted theoretically or confirmed experimentally in a limited number of Heusler alloys. Exploring new half-metallic Heusler alloys is necessary. In this study, the full-potential linearized augmented plane wave （FP_LAPW） method under density functional theory is utilized to investigate the electronic structures and magnetisms of semi-Heusler alloys CoCrTe and CoCrSb. In the calculations, the generalized gradient approximation （GGA） in the scheme of Perdew-Bueke-Ernzerhof is adopted to treat the exchange-correlation potential. The cutoff parameter is set to be Rmt × Kmax=9, where Rmt is the smallest atomic sphere radius and Kmax is the maximum value of the reciprocal lattice vector. Meshes （13× 13× 13 k-points） are used in the first Brillouin zone integration. Self-consistent calculations are considered to be convergent only when the integrated charge difference between the last two iterations is less than 1 × 10-4 e/cell. Spin-polarized calculations of the electronic structure for the semi-Heusler alloys CoCrTe and CoCrSb are performed. The calculations reveal that CoCrTe and CoCrSb at their equilibrium lattice constants are half-metallic ferromagnets with half-metallic gaps of 0.28 and 0.22 eV and total magnetic moments of 3.00 and 2.00 μB per formula unit, respectively. The calculated integer total magnetic moments （in μB） are consistent with the Slater-Pauling rule, Mt=Zt-18, where Zt denotes the total number of valence el

关 键 词：第一性原理 半金属 电子结构 磁性 

分 类 号：O469[理学—凝聚态物理]