International Center for Quantum Materials, School of Physics, Peking University, and Collaborative Innovation Center of Quantum Matter, 100871 Beijing, China.
Nanoscale. 2018 May 3;10(17):8153-8161. doi: 10.1039/c8nr00571k.
The quantum anomalous Hall (QAH) effect is a topologically nontrivial phase, characterized by a non-zero Chern number defined in the bulk and chiral edge states in the boundary. Using first-principles calculations, we demonstrate the presence of the QAH effect in a 1T-YN2 monolayer, which was recently predicted to be a Dirac half metal without spin-orbit coupling (SOC). We show that the inclusion of SOC opens up a large nontrivial bandgap of nearly 0.1 eV in the electronic band structure. This results in the nontrivial bulk topology, which is confirmed by the calculation of Berry curvature, anomalous Hall conductance and the presence of chiral edge states. Remarkably, a QAH phase of high Chern number C = 3 is found, and there are three corresponding gapless chiral edge states emerging inside the bulk gap. Different substrates are also chosen to study the possible experimental realization of the 1T-YN2 monolayer, while retaining its nontrivial topological properties. Our results open a new avenue in searching for QAH insulators with high temperature and high Chern numbers, which can have nontrivial practical applications.
量子反常霍尔（QAH）效应是一种拓扑非平庸相，其特征在于体相中存在非零陈数和边界上的手性边缘态。我们使用第一性原理计算证明了在最近被预测为没有自旋轨道耦合（SOC）的狄拉克半金属的 1T-YN2 单层中存在 QAH 效应。我们表明，SOC 的包含在电子能带结构中开辟了近 0.1 eV 的大非平庸带隙。这导致了非平凡的体拓扑，这通过贝里曲率、反常霍尔电导率和手性边缘态的存在得到了证实。值得注意的是，发现了具有高陈数 C = 3 的 QAH 相，并且在体隙内出现了三个对应的无带隙手性边缘态。还选择了不同的衬底来研究 1T-YN2 单层的可能实验实现，同时保留其非平凡的拓扑性质。我们的结果为寻找具有高温和高陈数的 QAH 绝缘体开辟了新途径，这些绝缘体可能具有重要的实际应用。
