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Nano Lett. 2017 Oct 11;17(10):6195-6202. doi: 10.1021/acs.nanolett.7b02855. Epub 2017 Oct 3.

Topological Dirac States beyond π-Orbitals for Silicene on SiC(0001) Surface.

Author information

1
Department of Physics, Xiangtan University , Xiangtan, Hunan 411105, China.
2
Department of Physics, The University of Texas at Austin , Austin, Texas 78712, United States.
3
School of Mechanical Engineering, Xiangtan University , Xiangtan, Hunan 411105, China.
4
College of Physics and Information Science, Hunan Normal University , Changsha 410081, China.
5
International Center for Quantum Materials, School of Physics, Peking University , Beijing 100871, China.
6
Key Laboratory of Computational Physical Sciences and Department of Physics, Fudan University , Shanghai 200433, China.

Abstract

The discovery of intriguing properties related to the Dirac states in graphene has spurred huge interest in exploring its two-dimensional group-IV counterparts, such as silicene, germanene, and stanene. However, these materials have to be obtained via synthesizing on substrates with strong interfacial interactions, which usually destroy their intrinsic π(pz)-orbital Dirac states. Here we report a theoretical study on the existence of Dirac states arising from the px,y orbitals instead of pz orbitals in silicene on 4H-SiC(0001), which survive in spite of the strong interfacial interactions. We also show that the exchange field together with the spin-orbital coupling give rise to a detectable band gap of 1.3 meV. Berry curvature calculations demonstrate the nontrivial topological nature of such Dirac states with a Chern number C = 2, presenting the potential of realizing quantum anomalous Hall effect for silicene on SiC(0001). Finally, we construct a minimal effective model to capture the low-energy physics of this system. This finding is expected to be also applicable to germanene and stanene and imply great application potentials in nanoelectronics.

KEYWORDS:

Dirac electrons; Silicene; first-principles calculations; topological properties

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