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Title: Electrical Transition in Isostructural VO 2 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 VO 2-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 2 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 VO 2 films. The strain trapping in VO 2 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 VO 2 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 (Δ V-V) in monoclinic structures which leads to a systematic decrease in the electronic bandgap of VO 2. Thus, this decrease in bandgap is additionally attributed to ferromagnetic ordering in the monoclinic phase to facilitate a Mottmore » insulator without going through the structural transition.« less

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [2];  [1]
  1. North Carolina State Univ., Raleigh, NC (United States)
  2. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1502563
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 9; Journal Issue: 1; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Moatti, Adele, Sachan, Ritesh, Cooper, Valentino R., and Narayan, Jagdish. Electrical Transition in Isostructural VO2 Thin-Film Heterostructures. United States: N. p., 2019. Web. doi:10.1038/s41598-019-39529-z.
Moatti, Adele, Sachan, Ritesh, Cooper, Valentino R., & Narayan, Jagdish. Electrical Transition in Isostructural VO2 Thin-Film Heterostructures. United States. doi:10.1038/s41598-019-39529-z.
Moatti, Adele, Sachan, Ritesh, Cooper, Valentino R., and Narayan, Jagdish. Thu . "Electrical Transition in Isostructural VO2 Thin-Film Heterostructures". United States. doi:10.1038/s41598-019-39529-z. https://www.osti.gov/servlets/purl/1502563.
@article{osti_1502563,
title = {Electrical Transition in Isostructural VO2 Thin-Film Heterostructures},
author = {Moatti, Adele and Sachan, Ritesh and Cooper, Valentino R. and Narayan, Jagdish},
abstractNote = {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. Thus, 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.},
doi = {10.1038/s41598-019-39529-z},
journal = {Scientific Reports},
number = 1,
volume = 9,
place = {United States},
year = {2019},
month = {2}
}

Journal Article:
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