Role of spin-orbit coupling and hybridization effects in the electronic structure of ultrathin Bi films
Role of spin-orbit coupling and hybridization effects in the electronic structure of ultrathin Bi films
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DOI：
10.1103/physrevlett.97.146803
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发表时间：
2006-10-06
影响因子：
8.6
通讯作者：
Hasegawa, S.
中科院分区：
文献类型：
--
作者：
Hirahara, T.;Nagao, T.;Hasegawa, S.
采用角分辨光谱学和第一性原理计算方法研究了Si(111)-7x7上Bi（001）超薄膜（厚度>= 7双层）的电子结构。与块体Bi的半金属性质相反，实验和理论都证明了由自旋轨道分裂表面态（SSs）形成的费米表面薄膜的金属性质对厚度的依赖性很小。在费米能级以下，我们清晰地探测到M ($) over bar点处的量子阱态（QWSs），令人惊讶地发现它们是非自旋轨道分裂的；薄膜是“电子对称的”，尽管顶部和底部界面的结构明显不相等。我们发现ssss在M ($) / bar附近与QWSs杂化，失去了自旋-轨道分裂的特征。
The electronic structure of Bi(001) ultrathin films (thickness >= 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 ($) over bar point, which were surprisingly found to be non-spin-orbit split; the films are "electronically symmetric" despite the obvious structural nonequivalence of the top and bottom interfaces. We found that the SSs hybridize with the QWSs near M ($) over bar and lose their spin-orbit-split character.