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arXiv 1503.05375cond-mat.mes-hall
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屈曲蜂窝晶格中应变可调的拓扑量子相变

Strain-tunable topological quantum phase transition in buckled honeycomb lattices

Jia-An Yan, Mack A. Dela Cruz, Salvador Barraza-Lopez, Li Yang

摘要:

低屈曲硅烯是一种典型的量子自旋霍尔绝缘体,其拓扑量子相变受面外电场控制。我们表明,这种场诱导的电子跃迁可以进一步调谐的平面内流体静力双轴应变$\varepsilon$,由于曲率相关的自旋轨道耦合(SOC):有一个$Z_2$ = 1的拓扑绝缘体相的双轴应变$|\varepsilon|$小于0.07,和带隙可以从0.7毫电子伏的$\varepsilon = +0.07$高达四倍的3.0毫电子伏的$\varepsilon = -0.07$。第一性原理计算还表明,临界场强$E_c$可以被调节113%以上,其绝对值比基于紧束缚模型的理论预测强近10倍.蜂窝晶格的屈曲结构因此增强了量子相变和SOC诱导的带隙的可调谐性,这对于基于二维材料的拓扑场效应晶体管的设计至关重要。

英文摘要:

Low-buckled silicene is a prototypical quantum spin Hall insulator with the topological quantum phase transition controlled by an out-of-plane electric field. We show that this field-induced electronic transition can be further tuned by an in-plane hydrostatic biaxial strain $\varepsilon$, owing to the curvature-dependent spin-orbit coupling (SOC): There is a $Z_2$ = 1 topological insulator phase for biaxial strain $|\varepsilon|$ smaller than 0.07, and the band gap can be tuned from 0.7 meV for $\varepsilon = +0.07$ up to a fourfold 3.0 meV for $\varepsilon = -0.07$. First-principles calculations also show that the critical field strength $E_c$ can be tuned by more than 113\%, with the absolute values nearly 10 times stronger than the theoretical predictions based on a tight-binding model. The buckling structure of the honeycomb lattice thus enhances the tunability of both the quantum phase transition and the SOC-induced band gap, which are crucial for the design of topological field-effect transistors based on two-dimensional materials.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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