Title: Cooperative effects of strain and electron correlation in epitaxial VO₂ and NbO₂

Abstract

Here, we investigate the electronic structure of the epitaxial VO₂ films in the rutile phase using the density functional theory combined with the slave spin method (DFT+SS). In DFT-SS, the multiorbital Hubbard interactions are added to a DFT-fit tight-binding model, and we employ the slave-spin method to treat the electron correlation. We find that while stretching the system along the rutile c-axis results in a band structure favoring an anisotropic orbital fillings, the electron correlation favors an equal electron filling among t_2g orbitals. These two distinct effects cooperatively induce interesting orbital-dependent redistributions of the electron occupations and the spectral weights, which pushes the strained VO₂ toward an orbital selective Mott transition (OSMT). The simulated single-particle spectral functions are directly compared to V L-edge resonant X-ray photoemission spectroscopy of epitaxial 10 nm VO₂/TiO₂ (001) and (100) strain orientations. Excellent agreement is observed between the simulations and experimental data regarding the strain-induced evolution of the lower Hubbard band. Simulations of rutile NbO₂ under similar strain conditions as VO₂ are performed, and we predict that OSMT will not occur in rutile NbO₂. Our results indicates that the electron correlation in VO₂ is important and can be modulated even in the rutile phase beforemore » the Peierls instability sets in.« less

Authors:

Lee, Wei -Cheng ^[1]; Wahila, Matthew J.  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-0569-4198"

Mukherjee, Shantanu ^[2]; Singh, Christopher N.  ^[1];

• Search DOE PAGES for author "Singh, Christopher N."
• Search DOE PAGES for ORCID "0000-0002-1975-5011"

Eustance, Tyler ^[1]; Regoutz, Anna  ^[3];

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Paik, H.  ^[4];

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• Search DOE PAGES for ORCID "0000-0002-8363-4679"

Boschker, Jos E.  ^[5];

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• Search DOE PAGES for ORCID "0000-0001-9122-2079"

Rodolakis, Fanny  ^[6];

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• Search DOE PAGES for ORCID "0000-0003-3359-4880"

Lee, Tien -Lin ^[7]; Schlom, D. G. ^[4]; Piper, Louis F. J.  ^[1]

• Search DOE PAGES for author "Piper, Louis F. J."
• Search DOE PAGES for ORCID "0000-0002-3421-3210"

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+ Show Author Affiliations

1. Binghamton Univ., Binghamton, NY (United States)
2. Indian Institute of Technology Chennai (India)
3. Imperial College London, London (United Kingdom)
4. Cornell Univ., Ithaca, NY (United States)
5. Leibniz-Institut fur Kristallzuchtung, Berlin (Germany)
6. Argonne National Lab. (ANL), Argonne, IL (United States)
7. Diamond Light Source, Didcot (United Kingdom)

Publication Date:

Wed Feb 20 00:00:00 EST 2019

Research Org.:

Argonne National Laboratory (ANL), Argonne, IL (United States)

Sponsoring Org.:

Air Force Research Laboratory (AFRL), Air Force Office of Scientific Research (AFOSR); National Science Foundation (NSF); USDOE

OSTI Identifier:

1495377

Grant/Contract Number:  

AC02-06CH11357

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Applied Physics

Additional Journal Information:

Journal Volume: 125; Journal Issue: 8; Journal ID: ISSN 0021-8979

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE