Department of Physics, Virginia Tech , Blacksburg, Virginia 24061, United States.
Nano Lett. 2017 Feb 8;17(2):963-972. doi: 10.1021/acs.nanolett.6b04299. Epub 2017 Jan 4.
Dirac semimetals (DSMs) have topologically robust three-dimensional Dirac (doubled Weyl) nodes with Fermi-arc states. In heterostructures involving DSMs, charge transfer occurs at the interfaces, which can be used to probe and control their bulk and surface topological properties through surface-bulk connectivity. Here we demonstrate that despite a band gap in DSM films, asymmetric charge transfer at the surface enables one to accurately identify locations of the Dirac-node projections from gapless band crossings and to examine and engineer properties of the topological Fermi-arc surface states connecting the projections, by simulating adatom-adsorbed DSM films using a first-principles method with an effective model. The positions of the Dirac-node projections are insensitive to charge transfer amount or slab thickness except for extremely thin films. By varying the amount of charge transfer, unique spin textures near the projections and a separation between the Fermi-arc states change, which can be observed by gating without adatoms.
狄拉克半金属（DSM）具有拓扑稳定的三维狄拉克（双倍 Weyl）节点和费米弧态。在涉及 DSM 的异质结构中，电荷转移发生在界面处，这可以通过表面-体连接来探测和控制它们的体和表面拓扑性质。在这里，我们证明尽管 DSM 薄膜存在带隙，但表面的不对称电荷转移使得人们能够从无带隙带交叉准确识别狄拉克节点投影的位置，并通过使用第一性原理方法和有效模型模拟吸附原子的 DSM 薄膜来检查和设计连接投影的拓扑费米弧表面态的性质。除了极薄的薄膜外，狄拉克节点投影的位置对电荷转移量或薄片厚度不敏感。通过改变电荷转移量，可以在投影附近观察到独特的自旋织构和费米弧态之间的分离，而无需吸附原子即可通过门控观察到这些变化。
