Chiral edge modes inherent to the topological quantum anomalous Hall (QAH) effect are a pivotal topic of contemporary condensed matter research aiming at future quantum technology and application in spintronics. A large topological gap is vital to protecting against thermal fluctuations and thus enabling a higher operating temperature. From first-principles calculations, we propose ${\mathrm{Al}}_2{\mathrm{O}}_3$ as an ideal substrate for atomic monolayers consisting of Bi and group-III elements, in which a large-gap quantum spin Hall effect can be realized. Additional half-passivation with nitrogen then suggests a topological phase transition to a large-gap QAH insulator. By effective tight-binding modeling, we demonstrate that Bi-III monolayer/${\mathrm{Al}}_2{\mathrm{O}}_3$ is dominated by $p_x,p_y$ orbitals, with subdominant $p_z$ orbital contributions. The topological phase transition into the QAH is induced by Zeeman splitting, where the off-diagonal spin exchange does not play a significant role. The effective model analysis promises utility far beyond Bi-III monolayer/${\mathrm{Al}}_2{\mathrm{O}}_3$, as it should generically apply to systems dominated by $p_x,p_y$ orbitals with a band inversion at $\mathrm{\Gamma }$.

中文翻译：

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功能化屈曲 Bi-III 单层/Al2O3 诱导的大能隙量子反常霍尔态

拓扑量子反常霍尔（QAH）效应固有的手征边缘模式是当代凝聚态研究的关键课题，旨在未来量子技术和自旋电子学中的应用。较大的拓扑间隙对于防止热波动并因此实现更高的工作温度至关重要。根据第一性原理计算，我们建议${铝}_2{\mathrm{○}}_3$作为由Bi和III族元素组成的原子单分子层的理想衬底，其中可以实现大间隙量子自旋霍尔效应。然后用氮进行额外的半钝化表明拓扑相变到大间隙 QAH 绝缘体。通过有效的紧束缚建模，我们证明了 Bi-III 单层/${铝}_2{\mathrm{○}}_3$由$p_X,p_{\mathrm{是的}}$轨道，具有次优势$p_z$轨道贡献。到 QAH 的拓扑相变是由塞曼分裂引起的，其中非对角自旋交换不起重要作用。有效的模型分析承诺远远超出 Bi-III 单层/${铝}_2{\mathrm{○}}_3$，因为它通常应该适用于由$p_X,p_{\mathrm{是的}}$带反转的轨道$\mathrm{\Gamma }$.