Suppression and emergence of charge-density waves at the surfaces of layered 1T-TiSe2 and 1T-TaS2 by in situ Rb deposition
Suppression and emergence of charge-density waves at the surfaces of layered 1T-TiSe2 and 1T-TaS2 by in situ Rb deposition
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DOI：
10.1088/1367-2630/12/12/125018
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发表时间：
2010-12-22
影响因子：
3.3
通讯作者：
Rossnagel, K
中科院分区：
文献类型：
--
作者：
Rossnagel, K
利用实时角分辨光电子能谱（XPS）原位测量了层状电荷密度波材料1 T-TiSe 2和1 T-TaS 2在Rb沉积过程中表面电子结构的变化。对于1 T-TiSe_2，在80 K的样品温度下，Rb的吸附引起了从脏半导体到金属的转变，在此过程中p（2 × 2 × 2）电荷密度波被完全抑制。对于1 T-TaS 2，Rb在室温下吸附后迅速嵌入，导致明显的金属到绝缘体的转变，这与从原始的几乎相称的p（root 13 x root 13）R13.9度超晶格到相称的c（2 root 3 x 4）rect的结构变化相关。电荷密度波相位在这两种化合物的电荷密度波机制的结果的影响进行了讨论，特别是参考可能的相互作用的电子-声子和电子-电子相互作用。有人建议，强烈的电子-声子耦合驱动的电荷密度波（CDW）相变在原始的1 T-TiSe 2以及在Rb插入1 T-TaS 2，即转换被解释为主要Peierls类不稳定性，或者换句话说，Jahn-Teller带不稳定性。
In situ real-time angle-resolved photoelectron spectroscopy is used to measure the electronic structure changes at the surfaces of the layered charge-density-wave materials 1T-TiSe2 and 1T -TaS2 during Rb deposition. For 1T-TiSe2, Rb adsorption at a sample temperature of 80K causes a transition from a dirty semiconductor to a metal, in the course of which the p(2 x 2 x 2) charge-density wave is completely suppressed. For 1T-TaS2, Rb adsorption at room temperature is rapidly followed by intercalation, leading to a pronounced metal-to-insulator transition that is correlated with a structural change from the pristine nearly commensurate p(root 13 x root 13)R13.9 degrees superlattice to a commensurate c(2 root 3 x 4)rect. charge-density-wave phase. The implications of the results on the charge-density-wave mechanisms in both compounds are discussed with particular reference to the possible interplay of electron-phonon and electron-electron interactions. It is suggested that strong electron-phonon coupling drives the charge-density wave (CDW) phase transitions in pristine 1T-TiSe2 as well as in Rb intercalated 1T-TaS2, i.e. the transitions are interpreted as primarily Peierls-like instabilities or, in other words, Jahn-Teller band instabilities.