Orbital-assisted metal-insulator transition in VO2.
We found direct experimental evidence for an orbital switching in the V 3d states across the metal-insulator transition in VO2. We have used soft-x-ray absorption spectroscopy at the V L2,3 edges as a sensitive local probe and have determined quantitatively the orbital polarizations. These results strongly suggest that, in going from the metallic to the insulating state, the orbital occupation changes in a manner that charge fluctuations and effective bandwidths are reduced, that the system becomes more one dimensional and more susceptible to a Peierls-like transition, and that the required massive orbital switching can only be made if the system is close to a Mott insulating regime.
Haverkort
M W
MW
II. Physikalisches Institut, Universität zu Köln, Zülpicher Strasse 77, D-50937 Köln, Germany.
Hu
Z
Z
Tanaka
A
A
Reichelt
W
W
Streltsov
S V
SV
Korotin
M A
MA
Anisimov
V I
VI
Hsieh
H H
HH
Lin
H-J
HJ
Chen
C T
CT
Khomskii
D I
DI
Tjeng
L H
LH