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Electronic structure of metallic and insulating phases of vanadium dioxide and its oxide alloys

Haichang Lu, Yuzheng Guo Orcid Logo, John Robertson

Physical Review Materials, Volume: 3, Issue: 9

Swansea University Author: Yuzheng Guo Orcid Logo

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Abstract

VO2 attracts much attention due to its metal-insulator transition. Alloying VO2 with MgO and GeO2 allows the band gap and the transition temperature to be varied. We find that the spin order plays a key role in creating the band gap in the low-temperature M1 phase. For MgO alloying, the alloying fra...

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Published in: Physical Review Materials
ISSN: 2475-9953
Published: 2019
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa52356
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Abstract: VO2 attracts much attention due to its metal-insulator transition. Alloying VO2 with MgO and GeO2 allows the band gap and the transition temperature to be varied. We find that the spin order plays a key role in creating the band gap in the low-temperature M1 phase. For MgO alloying, the alloying fraction n (MgnV1−nO2−n) is varied from 12.5 to 33.3%. The minimum band gap does not change without a structural rearrangement because both band edges of insulating VO2 consist of only V 3d states on sixfold-coordinated V sites. A crystal search finds that if the Mg fraction in the alloy is large enough (>20%), fivefold-coordinated V sites can have lower energy than the sixfold sites, and the band gaps are doubled. For GeO2 alloying, the insulating M1 structure reverts to rutile because GeO2 has a rutile phase. The result matches the experimental observation and is very important in guiding VO2's applications such as smart coating and nonlinear resistor.
College: Faculty of Science and Engineering
Issue: 9