Jiang Xingxing, Feng Yexin, Chen Ke-Qiu, Tang Li-Ming
Department of Applied Physics, School of Physics and Electronics, Hunan University, Changsha 410082, People's Republic of China.
J Phys Condens Matter. 2020 Mar 6;32(10):105501. doi: 10.1088/1361-648X/ab58f1. Epub 2019 Nov 19.
The coexistence of ferroelectricity and topological phase transition in monolayer α-InSe through strain engineering are investigated by first-principles calculation. The results show that with the spontaneous polarization increasing, the transition barrier decreases, approximately linearly related to the applied strain, and the effect of biaxial compressive strain within the in-plane is two orders of magnitude greater than that of tensile strain along the out-of-plane. The results also show that a Dirac cone with a linear dispersion relationship occurs at the high symmetry Γ point within the Brillouin region whatever strain pattern is applied. By analyzing the orbital characters of the electronic states near the Fermi level we find that the electronic structure presents obvious topological phase transition, indicating that monolayer α-InSe is not only an excellent 2D ferroelectric material but also a topological material.
通过第一性原理计算研究了单层α-InSe中通过应变工程实现的铁电性与拓扑相变的共存。结果表明，随着自发极化的增加，转变势垒降低，与施加的应变近似呈线性关系，面内双轴压缩应变的影响比沿面外拉伸应变的影响大两个数量级。结果还表明，无论施加何种应变模式，在布里渊区的高对称Γ点都会出现具有线性色散关系的狄拉克锥。通过分析费米能级附近电子态的轨道特征，我们发现电子结构呈现出明显的拓扑相变，这表明单层α-InSe不仅是一种优异的二维铁电材料，也是一种拓扑材料。
