Yang Yanmei, Liu Yang, Man Baoyuan, Zhao Mingwen, Li Weifeng
College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Normal University Jinan 250014 China.
School of Physics, State Key Laboratory of Crystal Materials, Shandong University Jinan 250100 China
RSC Adv. 2019 Jun 3;9(30):17203-17210. doi: 10.1039/c8ra08981g. eCollection 2019 May 29.
By using density functional theory calculations, we evaluated the effects of vacancy defects on the electronic and magnetic properties of MoS nanotubes. While both zigzag and armchair MoS tubes are intrinsically semiconducting, armchair (6, 6) tubes with simple disulfur and mono-molybdenum vacancies, as well as a large vacancy cluster consisting of both Mo and S vacancies (V ), and zigzag (10, 0) tubes with a mono-molybdenum defect are metallic. In particular, the (6, 6) tube with disulfur and V defects is half-metallic, which is promising for applications in spintronic devices. In addition, the (6, 6) tube exhibits an easily tunable magnetic property by introducing vacancies. We found that disulfur, mono-molybdenum, V , and V vacancies are able to cause spin polarization to induce net magnetic moment. This is mainly because the spin states prefer to couple through Mo atoms that are arranged along the zigzag direction (the axial direction of the armchair tube). In contrast, the zigzag (10, 0) tube is relatively hard to tune and is always nonmagnetic, except for the case of V . More importantly, atomic- and orbital-projected electron density of states analyses reveal that the net spins are mainly contributed by bare Mo atoms at or near the vacancy edge. For defect-laden MoS tubes that are still semiconducting, the energy gap and effective masses of the charge carriers are highly dependent on tube chirality and defect species. Our present findings highlight the worthwhile semiconducting, metallic, and half-metallic properties of MoS tubes, particularly armchair species, which can be obtained defect engineering; this can find broad applications for the fabrication of nanoelectronic and spintronic devices.
通过使用密度泛函理论计算，我们评估了空位缺陷对二硫化钼纳米管电子和磁性性质的影响。虽然锯齿形和扶手椅形二硫化钼管本质上都是半导体，但具有简单二硫空位和单钼空位的扶手椅形(6,6)管，以及由钼和硫空位组成的大空位簇(V)，和具有单钼缺陷的锯齿形(10,0)管都是金属性的。特别地，具有二硫和V缺陷的(6,6)管是半金属性的，这在自旋电子器件应用中很有前景。此外，(6,6)管通过引入空位表现出易于调节的磁性。我们发现二硫、单钼、V和V空位能够引起自旋极化以诱导净磁矩。这主要是因为自旋态倾向于通过沿锯齿方向(扶手椅管的轴向)排列的钼原子耦合。相比之下，锯齿形(10,0)管相对难以调节，除了V的情况外总是非磁性的。更重要的是，原子和轨道投影态密度分析表明，净自旋主要由空位边缘或其附近的裸钼原子贡献。对于仍为半导体的富含缺陷的二硫化钼管，电荷载流子的能隙和有效质量高度依赖于管的手性和缺陷种类。我们目前的研究结果突出了二硫化钼管，特别是扶手椅型二硫化钼管有价值的半导体、金属和半金属性质，这些性质可以通过缺陷工程获得；这可为纳米电子和自旋电子器件的制造找到广泛的应用。
