Spectroscopy and dynamics of unoccupied electronic states of the topological insulators Sb2Te3 and Sb2Te2S
Spectroscopy and dynamics of unoccupied electronic states of the topological insulators Sb2Te3 and Sb2Te2S
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DOI：
10.1103/physrevb.90.081106
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发表时间：
2014-08-13
影响因子：
3.7
通讯作者：
Hoefer, U.
中科院分区：
文献类型：
--
作者：
Reimann, J.;Guedde, J.;Hoefer, U.
采用时间和角度分辨双光子光电发射（2PPE）技术研究了掺磷拓扑绝缘体Sb2Te3及其衍生物Sb2Te2S的电子结构和超快电子动力学。我们的2PPE实验直接揭示了两种材料在费米能量以上都实现了拓扑表面态的无质量狄拉克锥类能量色散。与Sb2Te3相比，Sb2Te2S的体导带被转移到更高的能量。然而，令人惊讶的是，这种转变对拓扑表面态的电子动力学几乎没有影响，这是在皮秒时间尺度上进行的。
Time- and angle-resolved two-photon photoemission (2PPE) was used to study the electronic structure and ultrafast electron dynamics of the p-doped topological insulator Sb2Te3 and its derivative Sb2Te2S. Our 2PPE experiments directly reveal that the massless Dirac-cone like energy dispersion of topological surface states is realized above the Fermi energy in both materials. The observed bulk conduction bands of Sb2Te2S are found to be shifted to higher energies as compared to Sb2Te3. This shift has, however, surprisingly almost no influence on the electron dynamics in the topological surface state, which proceed on a picosecond time scale.