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Reducing orbital occupancy in VO 2 suppresses Mott physics while Peierls distortions persist

DOI: 10.1103/PhysRevB.96.081103 DOI Help

Authors: Nicholas F. Quackenbush (Binghamton University; National Institute of Standards and Technology) , Hanjong Paik (Cornell University) , Megan E. Holtz (Cornell University; Kavli Institute at Cornell for Nanoscale Science) , Matthew J. Wahila (Binghamton University) , Jarrett A. Moyer (University of Illinois at Urbana-Champaign) , Stefan Barthel (Universit├Ąt Bremen) , Tim O. Wehling (Universit├Ąt Bremen) , Dario A. Arena (University of South Florida) , Joseph C. Woicik (National Institute of Standards and Technology) , David A. Muller (Kavli Institute at Cornell for Nanoscale Science; 5Kavli Institute at Cornell for Nanoscale Science) , Darrell G. Schlom (Cornell University; Kavli Institute at Cornell for Nanoscale Science) , Louis Piper (Binghamton University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review B , VOL 96

State: Published (Approved)
Published: August 2017
Diamond Proposal Number(s): 12546 , 14730

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 Keywords: Electronic structure; Metal-insulator transition; Peierls transition; DFT+U; Hard x-ray photoelectron spectroscopy; Scanning transmission electron microscopy; X-ray absorption spectroscopy

Subject Areas: Materials, Physics

Instruments: I09-Surface and Interface Structural Analysis

Other Facilities: Advanced Light Source

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