Abstract
We perform first-principles calculations of mechanical and electronic properties of silicene under uniaxial strains. Poisson's ratio and the rigidity of silicene show strong chirality dependence under large uniaxial strains. The ultimate strains of silicene with uniaxial strain are smaller than those with biaxial strain. We find that uniaxial strains induce Dirac point deviation from the high-symmetry points in the Brillouin zone and semimetal-metal transitions. Therefore, no bandgap opens under the uniaxial strain. Due to its peculiar structure and variable sp3/sp2 ratio of the chemical bond, the deviation directions of Dirac points from the high-symmetry points in the Brillouin zone and variation of Fermi velocities of silicene exhibit significant difference from those of graphene. Fermi velocities show strong anisotropy with respect to the wave vector directions and change slightly before the semimetal-metal transition. We also find that the work function of silicene increases monotonously with the increasing uniaxial strains.PACS numbers61.46.-w; 62.20.D-; 73.22.Dj
Highlights
Silicene, the silicon analog of graphene, is a twodimensional honeycomb lattice of silicon atoms
We find that Poisson's ratio and rigidity of silicene show strong chirality dependence, and the ultimate strain of silicene under uniaxial strain is smaller than that under biaxial strain
We investigate the effect of uniaxial strains along two special directions of silicene: the armchair, AC, (x axis in Figure 1a) and zigzag, ZZ, (y axis in Figure 1a) directions
Summary
The silicon analog of graphene, is a twodimensional honeycomb lattice of silicon atoms It has been theoretically predicted long ago [1] but has only been synthesized recently [2,3,4,5,6,7,8,9,10]. Mechanical strain often brings about astonishing effects on properties of silicon materials It can improve the mobility of bulk Si [13,14], and strain engineering is considered to be one of the most promising strategies electronic properties of silicene [21,22,23,24,25,26,27,28]. Former studies of graphene [30,31,32,33,34,35] suggest that the uniaxial strain could introduce a new mechanism, and its effect needs to be studied cautiously
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