论文标题
二维拓扑半学，受符号对称性保护
Two-dimensional Topological Semimetals Protected by Symmorphic Symmetries
论文作者
论文摘要
二维（2D）频段越过半学（BCSM）可用于构建一系列新型的纳米级设备，例如超镜头和晶体管。我们发现，与先前提出的2D必需BCSM不同，形态对称性可以保护一种新型的鲁棒2D BCSM，该2D必需BCSM受非符号对称性保护[Young等，Phys。莱特牧师。 115，126803（2015）]。这种类型的对称对称性受保护（SSP）2D必需BCSM不能在不破坏晶体对称性的情况下将其歼灭，而不是意外带交叉引起的2D BCSM。通过小组理论分析，我们发现2D SSP BCSM只能在四个层组的Brillouin区（k'）的K（k'）点上存在，并将非磁性2d Feb2识别为候选者。有趣的是，非磁性2D SSP BCSM可以托管一对带交叉点（BCP），而非磁性三维（3D）Weyl半含量（WSMS）至少具有两对频带交叉点。发现单对BCP对任何种类的菌株都具有鲁棒性。此外，我们的计算表明，必需的2D SSP BCSM可用于实现自旋纹理的电场控制，因此是自旋装置的有希望的候选者。
Two-dimensional (2D) band crossing semimetals (BCSMs) could be used to build a range of novel nanoscale devices such as superlenses and transistors. We find that symmorphic symmetry can protect a new type of robust 2D BCSMs, unlike the previously proposed 2D essential BCSMs protected by non-symmorphic symmetry [Young et al., Phys. Rev. Lett. 115, 126803 (2015)]. This type of symmorphic symmetry protected (SSP) 2D essential BCSMs cannot be pair annihilated without destroying the crystalline symmetries, as opposed to the 2D BCSMs caused by the accidental band crossing. Through group theory analysis, we find that 2D SSP BCSMs can only exist at the K (K') point of Brillouin zone (BZ) of four layer groups and identify nonmagnetic 2D FeB2 as a candidate. Interestingly, nonmagnetic 2D SSP BCSMs can host a single pair of band crossing points (BCPs), whereas nonmagnetic three-dimensional (3D) Weyl semimetals (WSMs) have at least two pairs of band crossing Weyl points. It is found that the single pair of BCPs are robust against any kinds of strain. Furthermore, our calculation suggests that essential 2D SSP BCSMs can be used to realize electric field control of spin-texture, thus are promising candidates for spintronic devices.
