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arXiv 1702.01575cond-mat.mes-hall
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应变SnC的第一性原理和紧结合研究

First principle and tight-binding study of strained SnC

Y. Mogulkoc, M. Modarresi, A. Mogulkoc, Y. O. Ciftci, B. Alkan

摘要:

我们采用密度泛函理论和紧束缚模型研究了应变单层SnC的电子和光学性质。我们提取的跳跃参数紧束缚哈密顿单层SnC考虑DFT结果作为参考点。在密度泛函理论的框架下研究了声子谱,并利用Mulliken键布居分析了成键特性。此外,我们还发现了压应变SnC的带隙调制和从间接带隙到直接带隙的转变。在7.5%的拉伸应变下,带隙减小,最终发生半导体到半金属的转变。在紧束缚模型的框架下,讨论了自旋轨道耦合对能谱的影响。我们指出,虽然拉伸应变关闭的带隙,自旋轨道间隙仍然存在,这是$\sim 40$ meV的顺序在$Γ$点。在紧束缚近似下,衬底效应通过交错的亚晶格势来模拟。原始和应变的SnC的光学性质也检查在DFT方案。我们提出了在外加应变下介电函数实部和虚部的调制。

英文摘要:

We study the electronic and optical properties of strained single-layer SnC in the density functional theory (DFT) and tight-binding models. We extract the hopping parameters tight-binding Hamiltonian for monolayer SnC by considering the DFT results as a reference point. We also examine the phonon spectra in the scheme of DFT, and analyze the bonding character by using Mulliken bond population. Moreover, we show that the band gap modulation and transition from indirect to direct band gap in the compressive strained SnC. The applied tensile strain reduces the band gap and eventually the semiconductor to semimetal transition occurs for 7.5\% of tensile strain. In the framework of tight-binding model, the effect of spin-orbit coupling on energy spectrum are also discussed. We indicate that while tensile strain closes the band gap, spin-orbit gap is still present which is order of $\sim 40$ meV at the $Γ$ point. The substrate effect is modeled through a staggered sub-lattice potential in the tight-binding approximation. The optical properties of pristine and strained SnC are also examined in the DFT scheme. We present the modulation of real and imaginary parts of dielectric function under applied strain.

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