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 M2 phase is stabilized by nearly an order of magnitude more strain than expected for the measured temperature window. 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.
N. F. Quackenbush et al., "Stability of the M2 Phase of Vanadium Dioxide Induced by Coherent Epitaxial Strain," Physical Review B, vol. 94, no. 8, American Physical Society (APS), Aug 2016.
The definitive version is available at https://doi.org/10.1103/PhysRevB.94.085105
Materials Science and Engineering
International Standard Serial Number (ISSN)
Article - Journal
© 2016 American Physical Society (APS), All rights reserved.
01 Aug 2016