基于密度泛函理论(DFT),使用广义梯度近似(GGA)和局域密度近似(LDA)研究了Heusler合金Co2 MnAl1-xGex(x=0、0.25、0.5、0.75、1)的磁性和电子结构.随着掺杂浓度x的增加,合金的晶格常数和磁矩都线性增加,分别很好地满足Vegard和SP规律.对于整个合金系列,随x的增加,自旋向下带带隙宽度略有减少,费米面向高能移动.由于Co2 MnAl0.5Ge0.5合金的费米面恰好居于其自旋向下带带隙中部,此时合金具有最好的半金属稳定性,预期在磁隧道结器件中能实现高的自旋极化率.%Based on the density functional theory (DFT), the generalized gradient approximation method (GGA) and the local density approximation method (LDA) were applied to calculate the magnetism, electronic structures and half-metallicity of Heusler alloys Co2MnAl1-xGex(x=0,0. 25,0. 5,0. 75,1). The lattice parameters and the magnetic moment of the alloys increased linearly with increase of Ge content, meeting the vegard law and the S-P behavior well, respectively. Furthermore, the width of the spin-down gap slightly decreased and the fermi level moved up to higher energy level with increase of x. Since the fermi level locates in the middle of the spin-down gap, the Co2MnAl0. 5Ge0. 5 alloy presents a perfect half-metallic stability, and is expected to have a high spin polarization with the potential of magnetic tunnel junction application.
展开▼
