In:
Applied Physics Letters, AIP Publishing, Vol. 115, No. 25 ( 2019-12-16)
Abstract:
In this letter, a series of vanadium dioxide (VO2) epitaxial films were deliberately deposited on TiO2 substrates with different orientations [(001), (110), and (101)], in an attempt to gain insights into the strained VO2 epitaxial film. We found in-plane [100] and [1-10] directions, obviously anisotropic metal-insulator transition (MIT) in (110)-oriented VO2 films. In combination with synchrotron radiation high-resolution x-ray diffraction characterizations, electronic transport data reveal that the critical temperature of MIT depends on the strain state of the dimeric vanadium atomic chain along the c axis of the rutile phase. The anisotropy of MIT is closely related to the orientation of the VO2 films, which is caused by the varied orientation configuration of V-V atomic chain dimerization in the films. Soft x-ray absorption spectroscopy results further indicate that this anisotropy may be driven by the directional hybridization of O 2p and V 3d orbitals with respect to the orientation of VO2 thin films. The polarization-dependent V L-edge and O K-edge XAS data suggest that the elongation of the apical V-O bond length increases the p-d orbital overlap; thus, the energy level of the d// orbital is raised relative to that of the π* orbital. These anisotropic MIT behaviors will help us to understand how the strain engineering depends on the strain state of vanadium dimers in VO2 films.
Type of Medium:
Online Resource
ISSN:
0003-6951
,
1077-3118
Language:
English
Publisher:
AIP Publishing
Publication Date:
2019
detail.hit.zdb_id:
211245-0
detail.hit.zdb_id:
1469436-0
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