Date Awarded

2020

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Physics

Advisor

Henry Krakauer

Committee Member

Shiwei Zhang

Committee Member

Mumtaz Qazilbash

Committee Member

Marc Sher

Committee Member

Andreas Stathopoulos

Abstract

Upon cooling past a critical temperature $T_\mathrm{c}=\SI{340}{K}$ Vanadium dioxide (VO$_2$) exhibits a metal-insulator transition (MIT) from a metallic rutile R to an insulating monoclinic M1 phase. Other insulating phases, a monoclinic M2 and triclinic T, have been identified and are accessible via strain or doping. Despite decades of research, the nature of the VO$_2$ MIT is still not fully understood. In this work we present ab-initio hybrid density functional theory (DFT) calculations on the insulating phases, compare the results to experimental measurements and discuss their implications on our understanding of the VO$_2$ MIT. Recent measurements on M1 VO$_2$ under high pressure found a transition to a metallic monoclinic state X at $P_\mathrm{c}=\SI{34.3}{GPa}$. Following this increased interest in the study of VO$_2$ at high pressures, we will also present results of hybrid-DFT calculations on the M1 phase under increasing pressure. Our calculations predict that M1 may become metallic above $\sim\SI{32}{GPa}$, in good agreement with experiment.

DOI

http://dx.doi.org/10.21220/s2-8znr-g633

Rights

© The Author

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