Reducing orbital occupancy in VO2 suppresses Mott physics while Peierls distortions persist

Reducing orbital occupancy in VO2 suppresses Mott physics while Peierls distortions persist The characteristics of the cooperative Mott-Peierls metal-insulator transition (MIT) of VO2 can be altered by employing epitaxial strain. While the most commonly used substrate for this purpose is isostructural rutile TiO2, thin films often suffer from interdiffusion of Ti ions near the interface. Exploiting this phenomena, we investigate the nature of interfacial V4+/Ti4+ cation intermixing and its effects on the MIT using scanning transmission electron microscopy with electron energy loss spectroscopy (STEM-EELS), soft x-ray absorption spectroscopy (XAS), and hard x-ray photoelectron spectroscopy (HAXPES), along with supporting density functional theory (DFT) calculations. We find that the reduced orbital occupancy in highly Ti incorporated VO2 is responsible for suppressing the MIT. Interdiffused films are found to be metallic at all measured temperatures, despite a resolute dimerization inferred from x-ray absorption data at lower temperatures. Our results demonstrate that the Mott physics can be suppressed in doped VO2, while a lattice dimerization remains thermodynamically favorable. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Physical Review B American Physical Society (APS)

Reducing orbital occupancy in VO2 suppresses Mott physics while Peierls distortions persist

Abstract

The characteristics of the cooperative Mott-Peierls metal-insulator transition (MIT) of VO2 can be altered by employing epitaxial strain. While the most commonly used substrate for this purpose is isostructural rutile TiO2, thin films often suffer from interdiffusion of Ti ions near the interface. Exploiting this phenomena, we investigate the nature of interfacial V4+/Ti4+ cation intermixing and its effects on the MIT using scanning transmission electron microscopy with electron energy loss spectroscopy (STEM-EELS), soft x-ray absorption spectroscopy (XAS), and hard x-ray photoelectron spectroscopy (HAXPES), along with supporting density functional theory (DFT) calculations. We find that the reduced orbital occupancy in highly Ti incorporated VO2 is responsible for suppressing the MIT. Interdiffused films are found to be metallic at all measured temperatures, despite a resolute dimerization inferred from x-ray absorption data at lower temperatures. Our results demonstrate that the Mott physics can be suppressed in doped VO2, while a lattice dimerization remains thermodynamically favorable.
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Publisher
The American Physical Society
Copyright
Copyright © ©2017 American Physical Society
ISSN
1098-0121
eISSN
1550-235X
D.O.I.
10.1103/PhysRevB.96.081103
Publisher site
See Article on Publisher Site

Abstract

The characteristics of the cooperative Mott-Peierls metal-insulator transition (MIT) of VO2 can be altered by employing epitaxial strain. While the most commonly used substrate for this purpose is isostructural rutile TiO2, thin films often suffer from interdiffusion of Ti ions near the interface. Exploiting this phenomena, we investigate the nature of interfacial V4+/Ti4+ cation intermixing and its effects on the MIT using scanning transmission electron microscopy with electron energy loss spectroscopy (STEM-EELS), soft x-ray absorption spectroscopy (XAS), and hard x-ray photoelectron spectroscopy (HAXPES), along with supporting density functional theory (DFT) calculations. We find that the reduced orbital occupancy in highly Ti incorporated VO2 is responsible for suppressing the MIT. Interdiffused films are found to be metallic at all measured temperatures, despite a resolute dimerization inferred from x-ray absorption data at lower temperatures. Our results demonstrate that the Mott physics can be suppressed in doped VO2, while a lattice dimerization remains thermodynamically favorable.

Journal

Physical Review BAmerican Physical Society (APS)

Published: Aug 8, 2017

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