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arXiv · 1811.10070

Emergence of metallic monoclinic states of VO$_2$ films induced by K deposition

Daisuke Shiga·Makoto Minohara·Miho Kitamura·Ryu Yukawa·Koji Horiba·Hiroshi Kumigashira
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Abstract

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$_2$.

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Daisuke Shiga, Makoto Minohara, Miho Kitamura, Ryu Yukawa, Koji Horiba, Hiroshi Kumigashira. 2018-11-25. Emergence of metallic monoclinic states of VO$_2$ films induced by K deposition. https://doi.org/10.1103/physrevb.99.125120

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