Li Zheng, Zhang Jianing, Zhou Baozeng
Tianjin Key Laboratory of Film Electronic & Communicate Devices, School of Electrical and Electronic Engineering, Tianjin University of Technology, Tianjin 300384, China.
Phys Chem Chem Phys. 2020 Nov 25;22(45):26468-26477. doi: 10.1039/d0cp05028h.
A two-dimensional Dirac half-metal system, in which the 100% spin polarization and massless Dirac fermions can coexist, will show more advantages on the efficient spin injection and high spin mobility in spintronic devices. Moreover, it is attractive to achieve out-of-plane electric polarization in addition to the Dirac half-metal behavior, because this will open a new horizon in the field of multifunctional devices. In this work, a systematic study is made of Janus monolayers of Mn2X3Y3 (X, Y = Cl, Br and I, X ≠ Y) with asymmetric out-of-plane structural configurations, based on first-principles calculations. We demonstrate that monolayer Mn2X3Y3 freestanding films will remain stable experimentally by using the stability analysis. All the Janus monolayers show a ferromagnetic ground state and maintain their original DHM behavior. However, due to the large electric polarization, the hybridization intensities of Mn and the halogen atoms on both sides of Mn2Cl3I3 are very different, resulting in an obvious distortion of the spin-polarized Dirac cone. The distorted Dirac cone is repaired by the compression, indicating that strain can improve the orbital distortion induced by the electric polarization. All Mn2X3Y3 monolayer have in-plane magnetization anisotropy, which is mainly contributed by heavy halogen elements (Br and I), and the polarized substitution and biaxial strain will not change the easy magnetization orientation of the system. Thus, the electrically polarized Dirac half-metal system has potential for application in multifunctional spintronic devices.
一种二维狄拉克半金属系统，其中100%的自旋极化和无质量狄拉克费米子可以共存，在自旋电子器件的高效自旋注入和高自旋迁移率方面将展现出更多优势。此外，除了狄拉克半金属行为外，实现面外电极化也很有吸引力，因为这将为多功能器件领域开辟新的视野。在这项工作中，基于第一性原理计算，对具有不对称面外结构构型的Mn2X3Y3（X、Y = Cl、Br和I，X ≠ Y）的Janus单层进行了系统研究。我们通过稳定性分析表明，单层Mn2X3Y3独立薄膜在实验中能够保持稳定。所有Janus单层均呈现铁磁基态并保持其原始的狄拉克半金属行为。然而，由于较大的电极化，Mn2Cl3I3两侧的Mn与卤原子的杂化强度差异很大，导致自旋极化狄拉克锥明显畸变。通过压缩可以修复畸变的狄拉克锥，这表明应变可以改善由电极化引起的轨道畸变。所有Mn2X3Y3单层都具有面内磁化各向异性，这主要由重卤元素（Br和I）贡献，极化取代和双轴应变不会改变系统的易磁化方向。因此，电极化狄拉克半金属系统在多功能自旋电子器件中具有应用潜力。
