Thickness dependence of electronic structures in VO2 ultrathin films: Suppression of the cooperative Mott-Peierls transition
Thickness dependence of electronic structures in VO2 ultrathin films: Suppression of the cooperative Mott-Peierls transition
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DOI：
10.1103/physrevb.102.115114
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发表时间：
2020-09-09
影响因子：
3.7
通讯作者：
Kumigashira, H.
中科院分区：
文献类型：
--
作者：
Shiga, D.;Yang, B. E.;Kumigashira, H.
通过原位光发射光谱技术，研究了在TiO2（001）衬底上生长的可控尺寸VO2薄膜的电子结构和V-V二聚化的变化。在纳米结构薄膜中，带状佩尔斯跃迁和莫特跃迁的不稳定性之间的平衡被控制为厚度的函数。在VO2厚膜中，温度驱动的金属-绝缘体转变相关的特征光谱变化保持在1.5 nm（大致相当于沿[001]方向的5个V原子），而小于1.0 nm的VO2膜表现出绝缘性质，没有VO2的V-V二聚化特性。这些结果表明，Mott不稳定性和带状peerls不稳定性之间的微妙平衡在几纳米尺度上被尺寸交叉效应和约束效应调制，从而诱导出超薄VO2薄膜复杂的电子相图。
Through in situ photoemission spectroscopy, we investigated the change in the electronic structures and V-V dimerization of dimensionality-controlled VO2 films coherently grown on TiO2 (001) substrates. In the nanostructured films, the balance between the instabilities of a bandlike Peierls transition and a Mott transition is controlled as a function of thickness. The characteristic spectral change associated with temperature-driven metal-insulator transition in VO2 thick films holds down to 1.5 nm (roughly corresponding to five V atoms along the [001] direction), whereas VO2 films of less than 1.0 nm exhibit insulating nature without the V-V dimerization characteristic of VO2. These results suggest that the delicate balance between a Mott instability and a bandlike Peierls instability is modulated at a scale of a few nanometers by the dimensional crossover effects and confinement effects, which consequently induce the complicated electronic phase diagram of ultrathin VO2 films.