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arXiv 2003.06837cond-mat.mes-hallcond-mat.str-el
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压致IV族碲化物拓扑绝缘体相变的$GW$研究

$GW$ study of pressure-induced topological insulator transition in group IV-tellurides

Pablo Aguado-Puente, Stephen Fahy, Myrta Grüning

备注：
8 pages, 4 figures
发表信息：
Phys. Rev. Research 2, 043105 (2020)
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摘要：

采用密度泛函理论（DFT）和$G_0W_0$方法计算了窄禁带半导体PbTe、SnTe和GeTe的立方相电子结构.在DFT中，我们表明，与传统的半局域交换相关近似得到的带序是正确的SnTe和GeTe，但错误的PbTe。通过加入$G_0W_0$准粒子修正，恢复了高对称点L处的能带有序。然而，由于DFT单粒子态在靠近L的带边缘处的错误轨道特征，一次激发$G_0W_0$在能带结构中产生伪影。我们表明，为了纠正这些文物，它是足够的考虑非对角元素的$G_0W_0$自能对应于这些状态。我们还研究了这些材料的带隙的压力依赖性和从平凡到非平凡的能带结构的拓扑结构的过渡的可能性。对于PbTe，我们预测的频带交叉和拓扑转变发生在4.8 GPa左右。对于碲化锗，我们估计拓扑转变发生在1.9 GPa的约束立方相，压力低于一个结构的相变从菱面体立方。SnTe在环境压力下是晶体拓扑绝缘体，并且在大约$10\%$的体积膨胀下将发生向平凡拓扑的转变。

英文摘要：

We calculate the electronic structure of the narrow gap semiconductors PbTe, SnTe and GeTe in the cubic phase using density functional theory (DFT) and the $G_0W_0$ method. Within DFT, we show that the band ordering obtained with a conventional semilocal exchange-correlation approximation is correct for SnTe and GeTe but wrong for PbTe. The correct band ordering at the high-symmetry point L is recovered adding $G_0W_0$ quasiparticle corrections. However, one-shot $G_0W_0$ produces artifacts in the band structure due to the wrong orbital character of the DFT single-particle states at the band edges close to L. We show that in order to correct these artifacts it is enough to consider the off-diagonal elements of the $G_0W_0$ self-energy corresponding to these states. We also investigate the pressure dependence of the band gap for these materials and the possibility of a transition from a trivial to a non-trivial topology of the band structure. For PbTe, we predict the band crossover and topological transition to occur at around 4.8 GPa. For GeTe, we estimate the topological transition to occur at 1.9 GPa in the constrained cubic phase, a pressure lower than the one of the structural phase transition from rombohedral to cubic. SnTe is a crystalline topological insulator at ambient pressure, and the transition into a trivial topology would take place under a volume expansion of approximately $10\%$.

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