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arXiv 1807.06231cond-mat.mtrl-sci
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锑烯应变工程的第一性原理研究:力学和电学性质

Strain Engineering of Antimonene by a First-principles Study: Mechanical and Electronic Properties

Devesh R. Kripalani, Andrey A. Kistanov, Yongqing Cai, Ming Xue, Kun Zhou

摘要:

本文采用第一性原理计算研究了单层锑烯在其最稳定的β相中的力学和电子性质。发现其价带的上部区域仅由孤对p-轨道状态组成,其本质上比过渡金属二硫属化物中的d-轨道状态更离域,这意味着锑烯的优越输运性能。观察到β-锑烯的杨氏模量和剪切模量比本体锑的杨氏模量和剪切模量高约25%,而单层的六方晶格常数从本体中显著降低(约5%),表明层间耦合较强。β-锑烯在施加的单轴应变下的理想拉伸试验突出了6 GPa和8 GPa的理想强度,分别对应于Z字形和扶手椅方向上的15%和17%的临界应变。在变形过程中,材料的结构完整性被证明是更好地保存,虽然适度,在扶手椅方向。有趣的是,在Z字形和扶手椅方向上的单轴应变的应用揭示了电子能带结构中的方向依赖性趋势。我们发现,带隙的性质仍然不敏感的Z字形方向的应变,而在扶手椅方向的应变激活的间接直接带隙转变在4%的临界应变,由于带开关机制。在过渡期间,导带最小值的曲率增加,这表明在直接带隙配置中的电子的有效质量比在平衡的独立状态中的电子的有效质量轻。独立的β-锑烯的功函数为4.59 eV,并且在施加4%的双轴应变下达到最大值5.07 eV。

英文摘要:

In this work, we investigate the mechanical and electronic properties of monolayer antimonene in its most stable beta-phase using first-principles calculations. The upper region of its valence band is found to solely consist of lone pair p-orbital states, which are by nature more delocalized than the d-orbital states in transition metal dichalcogenides, implying superior transport performance of antimonene. The Young's and shear moduli of beta-antimonene are observed to be ~25% higher than those of bulk antimony, while the hexagonal lattice constant of the monolayer reduces significantly (~5%) from that in bulk, indicative of strong inter-layer coupling. The ideal tensile test of beta-antimonene under applied uniaxial strain highlights ideal strengths of 6 GPa and 8 GPa, corresponding to critical strains of 15% and 17% in the zigzag and armchair directions, respectively. During the deformation process, the structural integrity of the material is shown to be better preserved, albeit moderately, in the armchair direction. Interestingly, the application of uniaxial strain in the zigzag and armchair directions unveil direction-dependent trends in the electronic band structure. We find that the nature of the band gap remains insensitive to strain in the zigzag direction, while strain in the armchair direction activates an indirect-direct band gap transition at a critical strain of 4%, owing to a band switching mechanism. The curvature of the conduction band minimum increases during the transition, which suggests a lighter effective mass of electrons in the direct-gap configuration than in the free-standing state of equilibrium. The work function of free-standing beta-antimonene is 4.59 eV and it attains a maximum value of 5.07 eV under an applied biaxial strain of 4%.

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