Luo Fangxue, Hao Xiamin, Jia Yizhen, Yao Junjie, Meng Qingling, Zhai Shuwei, Wu Jinge, Dou Wenzhen, Zhou Miao
School of Physics, Beihang University, Beijing 100191, P. R. China.
Nanoscale. 2021 Feb 4;13(4):2527-2533. doi: 10.1039/d0nr06889f.
As novel states of quantum matter, quantum spin Hall (QSH) and quantum anomalous Hall (QAH) states have attracted considerable interest in condensed matter and materials science communities. Recently, a monolayer of the naturally occurring mineral jacutingaite (Pt2HgSe3), was theoretically proposed to be a large-gap QSH insulator and experimentally confirmed. Here, based on first-principles calculations and tight-binding modeling, we demonstrate QSH to QAH phase transition in jacutingaite by chemical functionalization with chalogen. We show that two-dimensional (2D) chalogenated jacutingaite, Pt2HgSe3-X (X = S, Se, Te), is ferromagnetic with Curie temperature up to 316 K, and it exhibits QAH effect with chiral edge states inside a sizeable topological gap. The physical mechanism lies in the adsorption induced transformation of the original Kane-Mele model into an effective four-band model involving (px, py) orbitals on a hexagonal lattice, so that the topological gap size can be controlled by spin-orbit coupling strength of the chalogen (0.28 eV for Pt2HgSe3-Te). These results not only show the promise of functionalization in orbital-engineering of 2D functional structures, but also provide an ideal and practical platform for achieving exotic topological phases for dissipationless transport and quantum computing.
作为量子物质的新状态，量子自旋霍尔（QSH）态和量子反常霍尔（QAH）态在凝聚态物理和材料科学领域引起了广泛关注。最近，理论上提出天然矿物贾库廷矿（Pt2HgSe3）的单层是一种大带隙QSH绝缘体，并得到了实验证实。在此，基于第一性原理计算和紧束缚模型，我们通过用硫族元素进行化学功能化，证明了贾库廷矿中从QSH到QAH的相变。我们表明，二维（2D）硫族化贾库廷矿Pt2HgSe3-X（X = S、Se、Te）是铁磁性的，居里温度高达316 K，并且在相当大的拓扑带隙内表现出手性边缘态的QAH效应。物理机制在于吸附诱导原始的凯恩-梅勒模型转变为一个有效的四能带模型，该模型涉及六边形晶格上的（px，py）轨道，从而拓扑带隙大小可以由硫族元素的自旋-轨道耦合强度控制（Pt2HgSe3-Te为0.28 eV）。这些结果不仅展示了功能化在二维功能结构轨道工程中的前景，而且为实现用于无耗散输运和量子计算的奇异拓扑相提供了一个理想且实用的平台。
