A synchrotron x-ray diffraction study of metal-insulator transitions in W-doped VO2 (V1-xWxO2) thin films has been carried out. The insulating phase for x≤0.07 exhibits cell-doubling with the V dimerization similar to bulk VO2, while the insulating phase for x≥0.11 does not. This result suggests that the electronic structure of the x≥0.11 insulators should be different from that of the x≤0.07 ones and bulk-insulating phase of VO2. The temperature and x dependence of superlattice reflection as observed casts doubt about the direct relationship between the dimerization of V ions and metal-insulator transition. The temperature dependence of the electrical resistivity rather implies the Mott-Anderson localization nature of the insulating phases. X-ray-induced persistent phase transitions are observed at low temperatures in each insulating phase in the vicinity of the boundary to the metallic phase regardless of the difference in the electronic structure. Gradual peak shift suggests that the x-ray irradiation produces nanometer metallic regions.
|ジャーナル||Physical Review B - Condensed Matter and Materials Physics|
|出版ステータス||Published - 2015 2月 3|
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