Emergence of metallic monoclinic states of VO2 films induced by K deposition
Emergence of metallic monoclinic states of VO2 films induced by K deposition
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DOI：
10.1103/physrevb.99.125120
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发表时间：
2018-11
影响因子：
3.7
通讯作者：
D. Shiga;M. Minohara;M. Kitamura;R. Yukawa;K. Horiba;H. Kumigashira
中科院分区：
文献类型：
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作者：
D. Shiga;M. Minohara;M. Kitamura;R. Yukawa;K. Horiba;H. Kumigashira
为了研究电子注入引起的VO 2金属化的原因，我们在TiO 2（001）衬底上生长VO 2薄膜，并在薄膜表面存款K原子，利用原位光电子能谱和X射线吸收谱研究了薄膜的电子结构和晶体结构的变化。K原子在绝缘单斜相VO 2表面的沉积导致了从绝缘体到金属的相变。在这种金属化状态下，单斜相VO 2的V-V二聚特征仍然存在，这一点由XAS谱的偏振依赖性所揭示。此外，单斜金属随着温度的降低经历向单斜绝缘体的转变，并且随着温度的升高经历向金红石金属的转变。这些结果表明，在电子掺杂的VO$_2$的情况下，在绝缘单斜相和金属金红石相之间的边界附近存在金属单斜相。
In order to study the origin of metallization of VO$_2$ induced by electron injection, we deposit K atoms onto the surface of VO$_2$ films grown on TiO$_2$ (001) substrates, and we investigate the change in the electronic and crystal structures using ${in~situ}$ photoemission spectroscopy and x-ray absorption spectroscopy (XAS). The deposition of K atoms onto a surface of insulating monoclinic VO$_2$ leads to a phase transition from insulator to metal. In this metallization state, the V-V dimerization characteristic to the monoclinic phase of VO$_2$ still exists, as revealed by the polarization dependence of the XAS spectra. Furthermore, the monoclinic metal undergoes a transition to a monoclinic insulator with decrease in temperature, and to a rutile metal with increase in temperature. These results indicate the existence of a metallic monoclinic phase around the boundary between the insulating monoclinic and metallic rutile phases in the case of electron-doped VO$_2$.