Density functional theory calculations within the generalized gradient approximation (GGA) are employed to study the ground state of Co2FeAl. Various magnetic configurations are considered to find out its most stable phase. The ferromagnetic ground state of the Co2FeAl is energetically observed with an optimized lattice constant of 5.70 Å. After that, the system was subjected under uniform and non-uniform strains, to see their effects on spin polarization (P) and half-metallicity. The effect of spin-orbit coupling is considered in the present study. Half-metallicity (and 100 % P) is retained only under uniform strains started from 0 to +4%, and dropped rapidly from 90% to 16% for the negative strains started from -1% to -6%. We find that the present system is much sensitive under tetragonal distortions as half-metallicity (and 100% P) is preserved only for the cubic case. The main reason for the loss of half-metallicity is due to the shift of the bands with respect to the Fermi level (EF). We also discuss the influence of these results on spintronics devices.

中文翻译：

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Co2FeAl Heusler 合金的相稳定性以及晶格畸变对电子性能和半金属铁磁性的影响：从头算研究


采用广义梯度近似 (GGA) 内的密度泛函理论计算来研究 Co2FeAl 的基态。考虑各种磁性配置来找出其最稳定的相位。 Co2FeAl 的铁磁基态以 5.70 Å 的优化晶格常数进行了积极观察。之后，系统受到均匀和非均匀应变，以观察它们对自旋极化（P）和半金属性的影响。本研究考虑了自旋轨道耦合的影响。仅在从 0 到 +4% 的均匀应变下才保留半金属度（和 100% P），并且对于从 -1% 到 -6% 的负应变，半金属度从 90% 迅速下降到 16%。我们发现本系统在四方畸变下非常敏感，因为仅在立方情况下保留了半金属性（和 100% P）。半金属性损失的主要原因是能带相对于费米能级（EF）的移动。我们还讨论了这些结果对自旋电子学器件的影响。