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Electrical Transition in Isostructural VO2 Thin-Film Heterostructures.


ABSTRACT: Control over the concurrent occurrence of structural (monoclinic to tetragonal) and electrical (insulator to the conductor) transitions presents a formidable challenge for VO2-based thin film devices. Speed, lifetime, and reliability of these devices can be significantly improved by utilizing solely electrical transition while eliminating structural transition. We design a novel strain-stabilized isostructural VO2 epitaxial thin-film system where the electrical transition occurs without any observable structural transition. The thin-film heterostructures with a completely relaxed NiO buffer layer have been synthesized allowing complete control over strains in VO2 films. The strain trapping in VO2 thin films occurs below a critical thickness by arresting the formation of misfit dislocations. We discover the structural pinning of the monoclinic phase in (10 ± 1 nm) epitaxial VO2 films due to bandgap changes throughout the whole temperature regime as the insulator-to-metal transition occurs. Using density functional theory, we calculate that the strain in monoclinic structure reduces the difference between long and short V-V bond-lengths (ΔV-V) in monoclinic structures which leads to a systematic decrease in the electronic bandgap of VO2. This decrease in bandgap is additionally attributed to ferromagnetic ordering in the monoclinic phase to facilitate a Mott insulator without going through the structural transition.

SUBMITTER: Moatti A 

PROVIDER: S-EPMC6395818 | biostudies-other | 2019 Feb

REPOSITORIES: biostudies-other

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Electrical Transition in Isostructural VO<sub>2</sub> Thin-Film Heterostructures.

Moatti Adele A   Sachan Ritesh R   Cooper Valentino R VR   Narayan Jagdish J  

Scientific reports 20190228 1


Control over the concurrent occurrence of structural (monoclinic to tetragonal) and electrical (insulator to the conductor) transitions presents a formidable challenge for VO<sub>2</sub>-based thin film devices. Speed, lifetime, and reliability of these devices can be significantly improved by utilizing solely electrical transition while eliminating structural transition. We design a novel strain-stabilized isostructural VO<sub>2</sub> epitaxial thin-film system where the electrical transition o  ...[more]

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