Large-gap quantum spin Hall (QSH) insulators were previously predicted in stanene and its derivatives. Beyond stanene that is the thinnest [Formula: see text]-Sn(111) film, we propose to explore QSH insulators in [Formula: see text]-Sn films with different crystallographic orientations. Our first-principles calculations reveal that the thickness-dependent band gap of [Formula: see text]-Sn(100) and [Formula: see text]-Sn(110) films does not show a monotonic decrease as typically expected by quantum confinement, but displays an oscillating change behavior, an indicative of topological quantum phase transition. While these films are normal insulators in the ultrathin limit, the QSH phase emerges above a critical film thickness of around 10 layers. Remarkably, the QSH insulators are obtainable within a wide thickness range and their energy gaps are sizable (even [Formula: see text][Formula: see text]0.1[Formula: see text]eV), which facilitates experimental realization of the high-temperature QSH effect.

中文翻译：

---

锡膜中的量子自旋霍尔绝缘体：超越 Stanene

大能隙量子自旋霍尔 (QSH) 绝缘体以前曾在 stanene 及其衍生物中被预测。除了最薄的锡烯[公式：见文本]-Sn(111) 薄膜，我们建议探索具有不同晶体取向的 [公式：见文本]-Sn 薄膜中的 QSH 绝缘体。我们的第一性原理计算表明，[公式：见文本]-Sn(100) 和 [公式：见文本]-Sn(110) 薄膜的厚度相关带隙没有显示出量子限制通常预期的单调减小，但显示出振荡变化行为，表明拓扑量子相变。虽然这些薄膜是超薄极限的普通绝缘体，但 QSH 相出现在约 10 层的临界薄膜厚度之上。值得注意的是，