Liu Ming-Yang, Li Guang-Qiang, He Yao, Xiong Kai
Department of Physics and Electronic Science, Chuxiong Normal University, Chuxiong 675000, P. R. China.
Department of Physics, Yunnan University, Kunming 650091, P. R. China.
Dalton Trans. 2024 Jun 25;53(25):10603-10617. doi: 10.1039/d4dt00856a.
Due to their novel spin and valley properties, two-dimensional (2D) ferrovalley materials are expected to be promising candidates for next-generation spintronic and valleytronic devices. However, they are subject to various defects in practical applications. Therefore, the electronic, valley, and magnetic properties may be modified in the presence of the defects. In this work, utilizing first-principles calculations, we systematically studied the effects of defects on the electronic, valley, and magnetic properties of the 2D ferrovalley material VSiN. It has been found that C doping, O doping, and N vacancies result in the half-metallic feature, Si vacancies result in the metallic feature, and V vacancies result in a bipolar gapless semiconductor. These defect-induced electronic properties can be effectively tuned by changing defect concentration and layer thickness. Since the impurity bands do not affect the K and K' valleys, valley polarization is well maintained in O-doped and N-defective systems. Importantly, these defects play a crucial role in modifying the magnetic properties of the pristine VSiN, especially the magnitude of local magnetic moments and the magnetic anisotropy energy. Detailed analysis of the density of states demonstrates that the variations of the total magnetic moment and magnetic anisotropy energy with biaxial strain are determined by the electronic states near the Fermi level rather than the type of defect, which provides a new understanding of the effects of defects on the magnetic properties of 2D materials. Moreover, the layer thickness can affect the magnetic coupling between defects and surrounding V atoms. Our results offer insight into the electronic, valley, and magnetic properties of VSiN in the presence of various point defects.
由于其独特的自旋和能谷特性，二维（2D）铁能谷材料有望成为下一代自旋电子学和能谷电子学器件的有前途的候选材料。然而，它们在实际应用中会受到各种缺陷的影响。因此，在存在缺陷的情况下，电子、能谷和磁性特性可能会发生改变。在这项工作中，我们利用第一性原理计算，系统地研究了缺陷对二维铁能谷材料VSiN的电子、能谷和磁性特性的影响。研究发现，C掺杂、O掺杂和N空位导致半金属特性，Si空位导致金属特性，而V空位导致双极无隙半导体。通过改变缺陷浓度和层厚度，可以有效地调节这些由缺陷引起的电子特性。由于杂质带不影响K和K'能谷，在O掺杂和N缺陷系统中能谷极化得以很好地保持。重要的是，这些缺陷在改变原始VSiN的磁性特性方面起着关键作用，特别是局部磁矩的大小和磁各向异性能量。对态密度的详细分析表明，总磁矩和磁各向异性能量随双轴应变的变化是由费米能级附近的电子态决定的，而不是由缺陷类型决定的，这为理解缺陷对二维材料磁性特性的影响提供了新的视角。此外，层厚度会影响缺陷与周围V原子之间的磁耦合。我们的结果为存在各种点缺陷时VSiN的电子、能谷和磁性特性提供了深入了解。
