skip to main content


Title: Electronic structure and insulating gap in epitaxial VO 2 polymorphs

Here, determining the origin of the insulating gap in the monoclinic VO 2(M1) is a long-standing issue. The difficulty of this study arises from the simultaneous occurrence of structural and electronic transitions upon thermal cycling. Here, we compare the electronic structure of the M1 phase with that of single crystalline insulating VO 2(A) and VO 2(B) thin films to better understand the insulating phase of VO 2. As these A and B phases do not undergo a structural transition upon thermal cycling, we comparatively study the origin of the gap opening in the insulating VO 2 phases. By x-ray absorption and optical spectroscopy, we find that the shift of unoccupied t 2g orbitals away from the Fermi level is a common feature, which plays an important role for the insulating behavior in VO 2 polymorphs. The distinct splitting of the half-filled t 2g orbital is observed only in the M1 phase, widening the bandgap up to ~0.6 eV. Our approach of comparing all three insulating VO 2 phases provides insight into a better understanding of the electronic structure and the origin of the insulating gap in VO 2.
 [1] ;  [1] ;  [2] ;  [3] ;  [1] ;  [1] ;  [4] ;  [5] ;  [2] ;  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Institute for Basic Science, Seoul (South Korea); Seoul National Univ., Seoul (South Korea)
  3. Chonnam National Univ., Gwangju (South Korea)
  4. Univ. of Kentucky, Lexington, KY (United States)
  5. Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725; AC02-06CH11357
Published Article
Journal Name:
APL Materials
Additional Journal Information:
Journal Volume: 3; Journal Issue: 12; Journal ID: ISSN 2166-532X
American Institute of Physics (AIP)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
36 MATERIALS SCIENCE; band gap; density functional theory; fermi levels; polymorphism; conduction bands
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1265959; OSTI ID: 1421224