Investigation of electronic properties of novel two-dimensional materials

我们主要研究了三种不同的材料：单层蓝光膦、单层GdAg_2和单晶LaBi。从LEED图案中，我们发现了一个完美的5x5上层建筑，这与以前的报道很好地吻合。ARPES测量证实了费米能级附近存在带隙。因此，蓝色光幻视是未来纳米器件的一个很好的候选者。GdAg_2单层膜是通过电子束蒸发器将纯Gd蒸发到干净的Ag（111）衬底上生长的。先前的MOKE和XMCD测量已经证实了这种材料中的铁磁顺序。在这里，使用ARPES，我们发现存在的外尔节线在这种材料。我们的理论合作者证实了我们的发现。现在，稿件已经提交，正在审核中，LaBi是拓扑绝缘体候选人。先前的实验报道了一些关于能带结构的ARPES结果，并得出LaBi具有拓扑Dirac锥的结论。然而，在这里，我们研究了LaBi的表面态的高分辨率ARPES和第一性原理计算。我们发现，否则拓扑非平凡的表面态是带杂化的缺口和表面态看起来像一个狄拉克节线。这项工作已经发表在Physical Review B上。[物理学修订版B 97，155153（2018）]

We mainly investigated three different materials: monolayer blue phosphene, monolayer GdAg2 and single crystal LaBi.Monolayer blue phosphene is grown by evaporating pieces of black phosphene onto a clean Au(111) substrate. From the LEED pattern, we find a perfect 5x5 superstructure, which is in good agreement with previous reports. The ARPES measurements have confirmed the existence of a band gap near the Fermi level. So blue phosphene is a good candidate for future nanodevices. The manuscript is still under preparation.Monolayer GdAg2 is grown by evaporating pure Gd from a e-beam evaporator onto a clean Ag(111) substrate. Previous MOKE and XMCD measurements have confirmed the ferromagnetic order in this material. Here, using ARPES, we found the existence of a Weyl nodal line in this material. Our theoretical collaborator confirmed our findings. Now, the manuscript has been submitted and is under review.LaBi is a topological insulator candidate. Previous experiments have reported some ARPES results on the band structures and concluded that LaBi have topological Dirac cones. However, here we studied the surface states of LaBi by high-resolution ARPES and first-principles calculations. We found that the otherwise topological nontrivial surface states are gapped out by band hybridization and the surface states looks like a Dirac nodal line. This work has already been published in Physical Review B. [Phys. Rev. B 97, 155153 (2018)]