Control of two-dimensional electronic states at anatase TiO2(001) surface by K adsorption
Control of two-dimensional electronic states at anatase TiO2(001) surface by K adsorption
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K吸附控制锐钛矿型TiO2(001)表面二维电子态
DOI：
10.1103/physrevb.97.165428
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发表时间：
2018
影响因子：
3.7
通讯作者：
Kumigashira H.
中科院分区：
文献类型：
--
作者：
Yukawa R.;Minohara M.;Shiga D.;Kitamura M.;Mitsuhashi T.;Kobayashi M.;Horiba K.;Kumigashira H.
在二氧化钛（a-）表面出现的有趣的金属电子结构的性质仍有待阐明，主要是由于难以控制由光照射产生的氧空位的深度分布。在本研究中，K原子被吸附到a-的（001）表面上，以将电子掺杂到a-中并将电子限制在表面区域。电子掺杂的成功和它的可控性，证实了performingin situangle-resolved光电子能谱以及核心水平的测量。在表面金属态中观察到清晰的子带结构，表明以可控的方式产生准二维电子液体（q2 DEL）态。随着电子掺杂（K吸附）的增加，q2 DEL状态表现出从具有源自长程Fröhlich相互作用的多声子损失结构的极化子液体状态到“弱相关金属”状态的交叉。在弱关联金属区的q2 DEL态中，在大约100 nm处清楚地观察到由于短程电子-声子耦合引起的扭结。特征能量小于以前观察到的三维性质的金属态的a-。这些结果表明，占主导地位的电子-声子耦合调制的各向异性载流子屏蔽q2 DEL状态。
The nature of the intriguing metallic electronic structures appearing at the surface of anatase titanium dioxide (a-) remains to be elucidated, mainly owing to the difficulty of controlling the depth distribution of the oxygen vacancies generated by photoirradiation. In this study, K atoms were adsorbed onto the (001) surface of a-to dope electrons into the a-and to confine the electrons in the surface region. The success of the electron doping and its controllability were confirmed by performingin situangle-resolved photoemission spectroscopy as well as core-level measurements. Clear subband structures were observed in the surface metallic states, indicating the creation of quasi-two-dimensional electron liquid (q2DEL) states in a controllable fashion. With increasing electron doping (K adsorption), the q2DEL states exhibited crossover from polaronic liquid states with multiple phonon-loss structures originating from the long-range Fröhlich interaction to “weakly correlated metallic” states. In the q2DEL states in the weakly correlated metallic region, a kink due to short-range electron–phonon coupling was clearly observed at about. The characteristic energy is smaller than that previously observed for the metallic states of a-with three-dimensional nature. These results suggest that the dominant electron–phonon coupling is modulated by anisotropic carrier screening in the q2DEL states.