Two types of Dirac-cone surface states on the (111) surface of topological crystalline insulator SnTe
Two types of Dirac-cone surface states on the (111) surface of topological crystalline insulator SnTe
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拓扑晶体绝缘体SnTe（111）面上的两种狄拉克锥表面态
DOI：
10.1103/physrevb.88.235125
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
and Y. Ando
中科院分区：
文献类型：
--
作者：
Y. Tanaka;T. Shoman;K. Nakayama;S. Souma;T. Sato;T. Takahashi;M. Novak;K. Segawa;and Y. Ando
我们使用角分辨光电子能谱直接测量的非孪晶单轴态的CaFeAs，铁基超导体的母体化合物的电子结构。非常小的光子束尺寸，结合晶体表面上相对大的单畴区域，使我们能够获得内在的非线性破碎的色散和费米面（FS）的几何形状沿着正交的Fe-Fe键方向没有任何机械或磁性退孪晶过程。比较优化的局域密度近似计算，引入了与轨道相关的能带位移以获得更好的一致性，这与轨道有序的发展是一致的。更有趣的是，在带中心附近观察到单向平直的FS段，这表明存在单向电荷密度波序。我们的研究结果表明，在CaFeAs强的电子各向异性和铁磷属元素化物系统的理论提出了强有力的限制。
We used angle-resolved photoemission spectroscopy to make direct measurements of the electronic structure of the untwinned uniaxial state of CaFeAs, the parent compound of an iron-based superconductor. The very small photon beam size, combined with the relatively large single-domain area on the crystal surfaces, allowed us to obtain the intrinsic symmetry-broken dispersions and Fermi surface (FS) geometries along the orthogonal Fe-Fe bond directions without any mechanical or magnetic detwinning processes. Comparing the optimized local density approximation calculations, an orbital-dependent band shifting is introduced to obtain better agreement, which is consistent with the development of orbital ordering. More interestingly, unidirectional straight and flat FS segments are observed near the zone center, which indicates the existence of a unidirectional charge density wave order. Our results indicate strong electronic anisotropy in CaFeAsand put strong constraints on theories for the iron-pnictide system.