Photoemission study of the metal-insulator transition inVO2/TiO2(001): Evidence for strong electron-electron and electron-phonon interaction
Photoemission study of the metal-insulator transition inVO2/TiO2(001): Evidence for strong electron-electron and electron-phonon interaction
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DOI：
10.1103/physrevb.69.165104
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发表时间：
2003-12
影响因子：
3.7
通讯作者：
K. Okazaki;H. Wadati;A. Fujimori;M. Onoda;Y. Muraoka;Z. Hiroi
中科院分区：
文献类型：
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作者：
K. Okazaki;H. Wadati;A. Fujimori;M. Onoda;Y. Muraoka;Z. Hiroi
我们对VO 2 /TiO 2（001）薄膜进行了详细的温度依赖性光发射研究，该薄膜在~ 300 K时显示出金属-绝缘体转变。通过在氧气气氛中退火薄膜获得了干净的表面。随着金属-绝缘子跃迁，谱权在相干部分和非相干部分之间的转移被清楚地观察到。我们还观察到在加热-冷却循环过程中光谱存在滞后性。我们推导出了金属相的“体”谱，发现它有很强的非相干部分。相干部分的宽度与带结构计算得到的宽度相当，但谱权减小，表明自能的动量依赖性显著。这是由于Zylbersztejn和Mott最初提出的不同d轨道之间的洪德规则耦合引起的铁磁波动。在绝缘阶段，v3d带宽度表现出较强的温度依赖性。我们将此归因于电子-声子相互作用，并使用具有非常大耦合常数的独立玻色子模型再现了它。
We have made a detailed temperature-dependent photoemission study of VO 2 /TiO 2 (001) thin films, which show a metal-insulator transition at ∼300 K. Clean surfaces were obtained by annealing the films in an oxygen atmosphere. Spectral weight transfer between the coherent and incoherent parts accompanying the metal-insulator transition was clearly observed. We also observed a hysteretic behavior of the spectra for heating-cooling cycles. We have derived the "bulk" spectrum of the metallic phase and found that it has a strong incoherent part. The width of the coherent part is comparable to that given by band-structure calculation in spite of its reduced spectral weight, indicating that the momentum dependence of the self-energy is significant. This is attributed to by ferromagnetic fluctuation arising from Hund's rule coupling between different d orbitals as originally proposed by Zylbersztejn and Mott. In the insulating phase, the width of the V 3d band shows strong temperature dependence. We attribute this to electron-phonon interaction and have reproduced it using the independent boson model with a very large coupling constant.