Wang Yue, Wang Liying, Mi Wenbo
Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparation Technology, School of Science, Tianjin University Tianjin 300354 China
Tianjin Demonstration Center for Experimental Physics Education, School of Science, Tianjin University Tianjin 300354 China.
RSC Adv. 2020 Jun 12;10(38):22556-22569. doi: 10.1039/d0ra03413d. eCollection 2020 Jun 10.
Highly spin-polarized half-metals (HMs) and spin-gapless semiconductors (SGSs) are the promising candidates in spintronic devices. However, the HM and SGS Heusler materials are very sensitive to the stoichiometric defects and lattice distortion, which will be not beneficial to the practical applications. Here, the electronic structure and magnetic properties of MnCoAl Ge ( = 0, 0.25, 0.50, 0.75 and 1.00) Heusler alloys were investigated by first-principles calculations. Large negative formation energy, cohesive energy and phonon spectra confirm that the MnCoAl Ge alloys are stable. It is found that MnCoAl Ge with = 0, 0.25, 0.75 and 1.00 show robust ferrimagnetic HM characteristics, while MnCoAlGe shows robust SGS characteristic. Under the hydrostatic and uniaxial strains, MnCoAl Ge exhibit a series of rich electronic transitions. The magnetic anisotropy of MnCoAl Ge turns from the in-plane [100] direction to the out-of-plane [001] one by applying the uniaxial strains. The results suggest that the complete spin polarizations of MnCoAl Ge alloys are robust against the stoichiometric defects and lattice distortion, which have potential applications in spintronic devices.
高自旋极化半金属（HMs）和自旋无隙半导体（SGSs）是自旋电子器件中很有前景的候选材料。然而，HM和SGS型赫斯勒材料对化学计量缺陷和晶格畸变非常敏感，这不利于实际应用。在此，通过第一性原理计算研究了MnCoAlGe（= 0、0.25、0.50、0.75和1.00）赫斯勒合金的电子结构和磁性。较大的负形成能、内聚能和声子谱证实了MnCoAlGe合金是稳定的。发现 = 0、0.25、0.75和1.00的MnCoAlGe表现出稳健的亚铁磁HM特性，而MnCoAlGe表现出稳健的SGS特性。在静水压力和单轴应变下，MnCoAlGe表现出一系列丰富的电子跃迁。通过施加单轴应变，MnCoAlGe的磁各向异性从面内[100]方向转变为面外[001]方向。结果表明，MnCoAlGe合金的完全自旋极化对化学计量缺陷和晶格畸变具有稳健性，在自旋电子器件中具有潜在应用。
