论文标题
狄拉克半学LAAGSB中的电子带结构和表面状态$ _ {2} $
Electronic band structure and surface states in Dirac semimetal LaAgSb$_{2}$
论文作者
论文摘要
laagsb $ _ {2} $是一种狄拉克半学，显示电荷密度波（CDW）顺序。先前的ARPES结果表明，沿$γ$ -M方向[X. Shi等人，物理。 Rev. B 93，081105（R）（2016）]。本文通过角度分辨光发射光谱（ARPES）和直接AB ISITION方法中的理论计算以及紧密的结合模型公式进行了对LAAGSB $ _ {2} $的电子带结构的复杂分析。为了研究可能的表面状态，我们对（001）表面进行了直接的DFT平板计算和表面绿色功能计算。表面状态的出现很大程度上取决于表面，这表明了LASB终止的结论是在切割的晶体中实现的。此外，通过我们的计算以$γ$预测的地面状态，$ x $点是Arpes发现的。还可以通过实验观察到沿X-R和M-A路径沿X-R和M-A路径存在的结节线。计算揭示了另一种淋巴结线，该线源于自旋轨道耦合的消失，并位于布里远区域边界的X-M-A-R平面。此外，我们分析了沿$γ$ -MM的验证路径的带结构，以验证是否可以预期狄拉克表面状态。他们在该地区的出现尚未确认。
LaAgSb$_{2}$ is a Dirac semimetal showing charge density wave (CDW) order. Previous ARPES results suggest the existence of the Dirac-cone-like structure in the vicinity of the Fermi level along the $Γ$-M direction [X. Shi et al., Phys. Rev. B 93, 081105(R) (2016)]. This paper is devoted to a complex analysis of the electronic band structure of LaAgSb$_{2}$ by means of angle-resolved photoemission spectroscopy (ARPES) and theoretical calculations within the direct ab initio method as well as tight binding model formulation. To investigate the possible surface states we performed the direct DFT slab calculation and the surface Green function calculation for the (001) surface. The appearance of the surface states, which depends strongly on surface, points to the conclusion that LaSb termination is realized in the cleaved crystals. Moreover, the surface states predicted by our calculations at the $Γ$ and $X$ points are found by ARPES. Nodal lines, which exist along X--R and M-A path due to crystal symmetry, are also observed experimentally. The calculations reveal another nodal lines, which originate from vanishing of spin-orbit coupling and are located at X-M-A-R plane at the Brillouin zone boundary. In addition, we analyze band structure along the $Γ$-M path to verify, whether Dirac surface states can be expected. Their appearance in this region is not confirmed.
