Chen Peng, Zou Jin-Yu, Liu Bang-Gui
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Phys Chem Chem Phys. 2017 May 31;19(21):13432-13437. doi: 10.1039/c7cp02158e.
The electronic, magnetic, and topological properties of a CoBr monolayer are studied in the framework of density-functional theory (DFT) combined with tight-binding (TB) modeling in terms of the Wannier basis. Our DFT investigation and Monte Carlo simulation show that there exists intrinsic two-dimensional ferromagnetism in the CoBr monolayer, thanks to the large out-of-plane magnetocrystalline anisotropic energy. Our further study indicates that the spin-orbit coupling makes it become a topologically nontrivial insulator with a quantum anomalous Hall effect and topological Chern number [script C] = 4 and its edge states can be manipulated by changing the width of its nanoribbons and applying strains. The CoBr monolayer can be exfoliated from the layered CoBr bulk material because its exfoliation energy is between those of graphene and the MoS monolayer and it is dynamically stable. These results make us believe that the CoBr monolayer can make a promising spintronic material for future high-performance devices.
在密度泛函理论（DFT）框架下，结合基于Wannier基的紧束缚（TB）模型，研究了CoBr单层的电子、磁性和拓扑性质。我们的DFT研究和蒙特卡罗模拟表明，由于面外磁晶各向异性能较大，CoBr单层中存在本征二维铁磁性。我们的进一步研究表明，自旋轨道耦合使其成为具有量子反常霍尔效应且拓扑陈数[C]=4的拓扑非平凡绝缘体，其边缘态可通过改变纳米带宽度和施加应变来调控。CoBr单层可以从层状CoBr块体材料中剥离出来，因为其剥离能介于石墨烯和MoS单层之间，且动力学稳定。这些结果使我们相信，CoBr单层有望成为未来高性能器件的自旋电子材料。
