Tensile strain along the cR-axis in epitaxial VO2 films raises the temperature of the metal insulator transition and is expected to stabilize the intermediate monoclinic M2 phase. We employ surface-sensitive x-ray spectroscopy to distinguish from the TiO2 substrate and identify the phases of VO2 as a function of temperature in epitaxial VO2/TiO2 thin films with well defined biaxial strain. Although qualitatively similar to our Landau–Ginzburg theory predicted phase diagrams, the stabilization of the M2 phase in epitaxial films results from nearly an order of magnitude more strain than expected. Our results reveal that the elongation of the cR axis is insufficient for describing the transition pathway of VO2 epitaxial films and that a strain induced increase of electron correlation effects must be considered.
|Journal||Physical Review B : Condensed Matter and Materials Physics|
|Publication status||Published - 5 Aug 2016|
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