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    Domain boundaries in silicene: Density functional theory calculations on electronic properties
    Xiao Hong-Jun (肖红君), Zhang Li-Zhi (张礼智), Du Shi-Xuan (杜世萱), Gao Hong-Jun (高鸿钧)
    Chin. Phys. B, 2015, 24 (8): 086806.   DOI: 10.1088/1674-1056/24/8/086806
    Abstract502)   HTML    PDF (1608KB)(887)      

    By using density functional theory (DFT)-based first-principles calculations, the structural stability and electronic properties for two kinds of silicene domain boundaries, forming along armchair edge and zigzag edge, have been investigated. The results indicate that a linkage of tetragonal and octagonal rings (4|8) appears along the armchair edge, while a linkage of paired pentagonal and octagonal rings (5|5|8) appears along the zigzag edge. Different from graphene, the buckling properties of silicene lead to two mirror symmetrical edges of silicene line-defect. The formation energies indicate that the 5|5|8 domain boundary is more stable than the 4|8 domain boundary. Similar to graphene, the calculated electronic properties show that the 5|5|8 domain boundaries exhibit metallic properties and the 4|8 domain boundaries are half-metal. Both domain boundaries create the perfect one-dimensional (1D) metallic wires. Due to the metallic properties, these two kinds of nanowires can be used to build the silicene-based devices.

    Comparison of electronic structure between monolayer silicenes on Ag (111)
    Chun-Liang Lin, Ryuichi Arafune, Maki Kawai, Noriaki Takagi
    Chin. Phys. B, 2015, 24 (8): 087307.   DOI: 10.1088/1674-1056/24/8/087307
    Abstract704)   HTML    PDF (1520KB)(373)      
    The electronic structures of monolayer silicenes (4×4 and √13×√13R13.9o) grown on Ag (111) surface are studied by scanning tunneling spectroscopy (STS) and density functional theory (DFT) calculations. While both phases have similar electronic structures around the Fermi level, significant differences are observed in the higher energy unoccupied states. The DFT calculations show that the contributions of Si 3pz orbitals to the unoccupied states are different because of their different buckled configurations.
    Antiferromagnetic and topological states in silicene: A mean field study
    Liu Feng (刘峰), Liu Cheng-Cheng (刘铖铖), Yao Yu-Gui (姚裕贵)
    Chin. Phys. B, 2015, 24 (8): 087503.   DOI: 10.1088/1674-1056/24/8/087503
    Abstract964)   HTML    PDF (1310KB)(479)      
    It has been widely accepted that silicene is a topological insulator, and its gap closes first and then opens again with increasing electric field, which indicates a topological phase transition from the quantum spin Hall state to the band insulator state. However, due to the relatively large atomic spacing of silicene, which reduces the bandwidth, the electron–electron interaction in this system is considerably strong and cannot be ignored. The Hubbard interaction, intrinsic spin orbital coupling (SOC), and electric field are taken into consideration in our tight-binding model, with which the phase diagram of silicene is carefully investigated on the mean field level. We have found that when the magnitudes of the two mass terms produced by the Hubbard interaction and electric potential are close to each other, the intrinsic SOC flips the sign of the mass term at either K or K' for one spin and leads to the emergence of the spin-polarized quantum anomalous Hall state.
ISSN 1674-1056   CN 11-5639/O4

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