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arXiv 2401.03028cond-mat.dis-nncond-mat.mes-hallcond-mat.mtrl-sci
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拓扑安德森绝缘体中的相变与标度不变性

Phase transitions and scale invariance in topological Anderson insulators

Bryan D. Assunção, Gerson J. Ferreira, Caio H. Lewenkopf

AI总结:

本文通过局域陈数标记研究二维BHZ模型中无序驱动的拓扑相变,发现中心元胞无序平均陈数满足单参数标度关系,并给出临界指数,揭示其普适标度行为。

摘要:

我们研究了二维(2D)系统中无序驱动的平庸绝缘体与拓扑绝缘体(TI)相之间的转变。我们的研究主要集中于具有安德森无序的BHZ模型,而其他标准2DTI模型表现出等价特征。分析基于局域陈数标记(LCM),这是一种局域量,可用于表征有限和无序系统中的拓扑转变。我们的模拟表明,无序驱动的平庸到拓扑绝缘体转变可以通过$\mathcal{C}_0$很好地刻画,$\mathcal{C}_0$是系统中心元胞附近的无序平均LCM。我们证明$\mathcal{C}_0$具有单参数标度行为,即$\mathcal{C}_0(M, W, L) \equiv \mathcal{C}_0(z)$,其中$z = [W^\mu-W_c^\mu(M)]L$,$M$是狄拉克质量,$W$是无序强度,$L$是系统尺寸,而$W_c(M) \propto \sqrt{M}$和$\mu\approx 2$分别代表临界无序强度和临界指数。我们的数值结果与基于一阶玻恩近似(1BA)分析的理论预言一致。这些观察使我们推测,我们所发现的普适标度函数对于非晶和无序驱动的拓扑相变是相当普遍的。

英文摘要:

We investigate disordered-driven transitions between trivial and topological insulator (TI) phases in two-dimensional (2D) systems. Our study primarily focuses on the BHZ model with Anderson disorder, while other standard 2DTI models exhibit equivalent features. The analysis is based on the local Chern marker (LCM), a local quantity that allows for the characterization of topological transitions in finite and disordered systems. Our simulations indicate that disorder-driven trivial to topological insulator transitions are nicely characterized by $\mathcal{C}_0$, the disorder averaged LCM near the central cell of the system. We show that $\mathcal{C}_0$ is characterized by a single-parameter scaling, namely, $\mathcal{C}_0(M, W, L) \equiv \mathcal{C}_0(z)$ with $z = [W^μ-W_c^μ(M)]L$, where $M$ is the Dirac mass, $W$ is the disorder strength and $L$ is the system size, while $W_c(M) \propto \sqrt{M}$ and $μ\approx 2$ stand for the critical disorder strength and critical exponent, respectively. Our numerical results are in agreement with a theoretical prediction based on a first-order Born approximation (1BA) analysis. These observations lead us to speculate that the universal scaling function we have found is rather general for amorphous and disorder-driven topological phase transitions.

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