Hirahara T, Nagao T, Matsuda I, Bihlmayer G, Chulkov E V, Koroteev Yu M, Echenique P M, Saito M, Hasegawa S
Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Phys Rev Lett. 2006 Oct 6;97(14):146803. doi: 10.1103/PhysRevLett.97.146803. Epub 2006 Oct 3.
The electronic structure of Bi(001) ultrathin films (thickness > or =7 bilayers) on Si(111)-7x7 was studied by angle-resolved photoemission spectroscopy and first-principles calculations. In contrast with the semimetallic nature of bulk Bi, both the experiment and theory demonstrate the metallic character of the films with the Fermi surface formed by spin-orbit-split surface states (SSs) showing little thickness dependence. Below the Fermi level, we clearly detected quantum well states (QWSs) at the M point, which were surprisingly found to be non-spin-orbit split; the films are "electronically symmetric" despite the obvious structural nonequivalence of the top and bottom interfaces. We found that the SSs hybridize with the QWSs near M and lose their spin-orbit-split character.
通过角分辨光电子能谱和第一性原理计算研究了Si(111)-7x7上Bi(001)超薄膜（厚度≥7个双层）的电子结构。与块状Bi的半金属性质不同，实验和理论均表明薄膜具有金属特性，其费米面由自旋轨道分裂表面态（SSs）形成，厚度依赖性很小。在费米能级以下，我们在M点清晰地检测到量子阱态（QWSs），令人惊讶的是，这些量子阱态未发生自旋轨道分裂；尽管顶部和底部界面在结构上明显不等价，但薄膜是“电子对称的”。我们发现，SSs在M点附近与QWSs发生杂化，并失去其自旋轨道分裂特性。
