物理学报2016，Vol.65Issue(12)：127501-1-127501-9,9.DOI:10.7498/aps.65.127501
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
摘要
Abstract
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 electrons and Mt means the total magnetic moment (in µB) per formula unit. Moreover, the spin moment of the Cr atom is obviously larger than those of the Co, Te, and Sb atoms. Co, Te and Sb are all antiferromagnetically coupled to Cr for CoCrTe and CoCrSb. The electronic structures of CoCrTe and CoCrSb are also calculated as their lattice constants change from −13% to +13% relative to the equilibrium lattice constant. The calculated results indicate that CoCrTe and CoCrSb can maintain their half-metallicities and retain their total magnetic moments of 3.00 and 2.00 µB per formula unit even as their lattice constants change from −11.4% to 9.0% and from −11.2% to 2.0%, respectively. The semi-Heusler alloys CoCrTe and CoCrSb should be useful in spintronics and other applications.关键词
第一性原理/半金属/电子结构/磁性Key words
first principle/half metal/electronic structure/magnetism引用本文复制引用
姚仲瑜,孙丽,潘孟美,孙书娟..第一性原理研究semi-Heusler合金CoCrTe和CoCrSb的半金属性和磁性∗[J].物理学报,2016,65(12):127501-1-127501-9,9.基金项目
国家自然科学基金(批准号:11364014,11364015)和海南省自然科学基金(批准号:113005,20165196)资助的课题.@@@@* Project supported by the National Natural Science Foundation of China (Grant Nos.11364014,11364015) and the Natural Science Foundation of Hainan Province, China (Grant Nos.113005,20165196) （批准号:11364014,11364015）
