Influence of Strain on VO<sub>2</sub> Stoichiometry and its Metal-Insulator Transition
ORAL
Abstract
VO2 is a canonical example of a strongly correlated system that exhibits a wide range of polymorphs such as monoclinic (M1, M2, T) and rutile (R) with each exhibiting unique electronic and optical properties. VO2 undergoes a metal-insulator transition (MIT) around 340K accompanied by a first order phase transition from high temperature metallic rutile phase to low temperature insulating monoclinic phase. Understanding and controlling this MIT by varying chemical composition, and external stimuli, such as strain, temperature, and electric field is necessary to realize VO2 based devices. In this talk, we will explore the coupling between experimentally realizable strain and oxygen vacancy (VOq) formation as well as diffusion energies in VO2 using beyond-DFT methods (e.g. DFT+U, meta- and hybrid DFT), benchmarked against very accurate many-body Quantum Monte Carlo (QMC) calculations. Theory predicts that strain facilitates electron-doping via creation of oxygen vacancies in VO2, consistent with our experimental findings on the strain control of the MIT in VO2 thin-films.
*This work was supported by the Center for Predictive Simulation of Functional Materials, through U.S. Department of Energy, Office of Science, Basic Energy Sciences, Computational Materials Sciences Program.
–
Presenters
-
Panchapakesan Ganesh
- Oak Ridge National Lab
- Oak Ridge National Laboratory
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory