Yaji Koichiro, Visikovskiy Anton, Iimori Takushi, Kuroda Kenta, Hayashi Singo, Kajiwara Takashi, Tanaka Satoru, Komori Fumio, Shin Shik
Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University, Fukuoka 819-0395, Japan.
Phys Rev Lett. 2019 Mar 29;122(12):126403. doi: 10.1103/PhysRevLett.122.126403.
The symmetry of a surface or interface plays an important role in determining the spin splitting and texture of a two-dimensional band. Spin-polarized bands of a triangular lattice atomic layer (TLAL) consisting of Sn on a SiC(0001) substrate is investigated by spin- and angle-resolved photoelectron spectroscopy. Surprisingly, both Zeeman- and Rashba-type spin-split bands, without and with spin degeneracy, respectively, coexist at a K point of the Sn TLAL. The K point has a threefold symmetry without inversion symmetry according to the crystal structure including the SiC periodicity, meaning that the Zeeman-type is consistent with the symmetry of the lattice while the Rashba-type is inconsistent. Our density functional calculations reveal that the charge density distribution of the Rashba-type (Zeeman-type) band shows (no) inversion symmetry at the K point. Therefore, the symmetry of the charge density distribution agrees with both types of the spin splitting.
表面或界面的对称性在决定二维能带的自旋分裂和织构方面起着重要作用。通过自旋和角分辨光电子能谱研究了由位于SiC(0001)衬底上的Sn组成的三角晶格原子层（TLAL）的自旋极化能带。令人惊讶的是，分别具有和不具有自旋简并的塞曼型和 Rashba 型自旋分裂能带在 Sn TLAL 的 K 点共存。根据包括 SiC 周期性的晶体结构，K 点具有三重对称性但没有反演对称性，这意味着塞曼型与晶格对称性一致，而 Rashba 型不一致。我们的密度泛函计算表明，Rashba 型（塞曼型）能带的电荷密度分布在 K 点显示（不显示）反演对称性。因此，电荷密度分布的对称性与两种类型的自旋分裂都相符。
