Two-dimensional honeycomb borophene oxide: strong anisotropy and nodal loop transformation
Two-dimensional honeycomb borophene oxide: strong anisotropy and nodal loop transformation
复制标题
二维蜂窝状硼烯氧化物：强各向异性和节环变换。
DOI：
10.1039/c8nr08729f
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发表时间：
2019
期刊：
影响因子：
6.7
通讯作者：
Gang Zhang
中科院分区：
文献类型：
--
作者：
Chengyong Zhong;Weikang Wu;Junjie He;Guangqian Ding;Yi Liu;Dengfeng Li;Shengyuan A. Yang;Gang Zhang
拓扑半金属的研究主要集中在重元素化合物上，而对轻元素材料的关注较少。然而，可以忽略的自旋轨道耦合轻元素可能是有益的实现拓扑带功能。本文利用第一性原理计算，提出了一种新的二维轻元素材料--蜂窝状硼氧化物（h-B2 O），它具有非平凡的拓扑性质。所提出的结构是基于最近在Al（111）衬底上合成的蜂窝状硼化物[W.利湖，加-地孔角，澳-地Chen，J. Gou，S.盛，W. Zhang，H.利湖，加-地Chen，P. Cheng和K. Wu，Sci.公牛，2018，63，282-286]。与石墨烯或硅烯的氧化物不同，h-B2 O单层是完全平坦的。我们系统地研究了h-B2 O的结构性质，发现它具有很好的稳定性和显著的力学各向异性。有趣的是，h-B2 O的电子能带结构在布里渊区的Y点周围有一个节点环，受到镜像对称性的保护。此外，在适度的晶格应变下，单个节环可以转化为两个环，每个环都穿过布里渊区。在过渡之前和之后的循环的特征在于不同的？X的？拓扑指数我们的工作不仅预测了一种新的二维材料，具有有趣的物理性质，而且还提供了一种替代方法来寻找新的拓扑相在二维轻元素系统。
The search for topological semimetals is mainly focused on heavy-element compounds by following the footsteps of previous research on topological insulators, with less attention on light-element materials. However, the negligible spin orbit coupling with light elements may turn out to be beneficial for realizing topological band features. Here, using first-principles calculations, we propose a new two-dimensional light-element materialthe honeycomb borophene oxide (h-B2O), which has nontrivial topological properties. The proposed structure is based on the recently synthesized honeycomb borophene on an Al (111) substrate [W. Li, L. Kong, C. Chen, J. Gou, S. Sheng, W. Zhang, H. Li, L. Chen, P. Cheng and K. Wu, Sci. Bull., 2018, 63, 282-286]. The h-B2O monolayer is completely flat, unlike the oxides of graphene or silicene. We systematically investigate the structural properties of h-B2O, and find that it has very good stability and exhibits significant mechanical anisotropy. Interestingly, the electronic band structure of h-B2O hosts a nodal loop centered around the Y point in the Brillouin zone, protected by the mirror symmetry. Furthermore, under moderate lattice strain, the single nodal loop can be transformed into two loops, each penetrating through the Brillouin zone. The loops before and after the transition are characterized by different ? x ? topological indices. Our work not only predicts a new two-dimensional material with interesting physical properties, but also offers an alternative approach to search for new topological phases in 2D light-element systems...