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Topological Insulator in Two-Dimensional SiGe Induced by Biaxial Tensile Strain
ACS Omega ( IF 3.7 ) Pub Date : 2018-01-02 00:00:00 , DOI: 10.1021/acsomega.7b01957 Tamiru Teshome 1 , Ayan Datta 1
ACS Omega ( IF 3.7 ) Pub Date : 2018-01-02 00:00:00 , DOI: 10.1021/acsomega.7b01957 Tamiru Teshome 1 , Ayan Datta 1
Affiliation
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Strain-engineered two-dimensional (2D) SiGe is predicted to be a topological insulator (TI) based on first-principle calculations. The dynamical and thermal stabilities were ascertained through phonon spectra and ab initio molecular dynamics simulations. 2D SiGe remains dynamically stable under tensile strains of 4 and 6%. A band inversion was observed at the Γ-point with a band gap of 25 meV for 6% strain due to spin–orbit coupling interactions. Nontrivial of the TI phase was determined by its topological invariant (υ = 1). For SiGe nanoribbon with edge states, the valence band and conduction band cross at the Γ-point to create a topologically protected Dirac cone inside the bulk gap. We found that hexagonal boron nitride (h-BN) with high dielectric constant and band gap can be a very stable support to experimentally fabricate 2D SiGe as the h-BN layer does not alter its nontrivial topological character. Unlike other heavy-metal-based 2D systems, because SiGe has a sufficiently large gap, it can be utilized for spintronics and quantum spin Hall-based applications under ambient condition.
中文翻译：
双轴拉伸应变在二维SiGe中的拓扑绝缘体
基于第一性原理计算，将应变工程二维（2D）SiGe预测为拓扑绝缘体（TI）。通过声子光谱和从头算分子动力学模拟确定了动力学和热稳定性。2D SiGe在4和6％的拉伸应变下保持动态稳定。由于自旋-轨道耦合作用，在6％应变下，在Γ点观察到带隙为25 meV的带隙。TI相的不平凡由其拓扑不变性（υ= 1）决定。对于具有边缘状态的SiGe纳米带，价带和导带在Γ点处交叉，从而在体隙内创建了一个受拓扑保护的Dirac锥。我们发现具有高介电常数和带隙的六方氮化硼（h-BN）可以作为实验制造2D SiGe的非常稳定的支撑，因为h-BN层不会改变其非平凡的拓扑特征。与其他基于重金属的2D系统不同，由于SiGe具有足够大的间隙，因此可以在环境条件下将其用于自旋电子学和基于量子自旋霍尔的应用。
更新日期：2018-01-02
中文翻译：
双轴拉伸应变在二维SiGe中的拓扑绝缘体
基于第一性原理计算，将应变工程二维（2D）SiGe预测为拓扑绝缘体（TI）。通过声子光谱和从头算分子动力学模拟确定了动力学和热稳定性。2D SiGe在4和6％的拉伸应变下保持动态稳定。由于自旋-轨道耦合作用，在6％应变下，在Γ点观察到带隙为25 meV的带隙。TI相的不平凡由其拓扑不变性（υ= 1）决定。对于具有边缘状态的SiGe纳米带，价带和导带在Γ点处交叉，从而在体隙内创建了一个受拓扑保护的Dirac锥。我们发现具有高介电常数和带隙的六方氮化硼（h-BN）可以作为实验制造2D SiGe的非常稳定的支撑，因为h-BN层不会改变其非平凡的拓扑特征。与其他基于重金属的2D系统不同，由于SiGe具有足够大的间隙，因此可以在环境条件下将其用于自旋电子学和基于量子自旋霍尔的应用。
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