Mott transition in VO2 revealed by infrared spectroscopy and nano-imaging.
Electrons in correlated insulators are prevented from conducting by Coulomb repulsion between them. When an insulator-to-metal transition is induced in a correlated insulator by doping or heating, the resulting conducting state can be radically different from that characterized by free electrons in conventional metals. We report on the electronic properties of a prototypical correlated insulator vanadium dioxide in which the metallic state can be induced by increasing temperature. Scanning near-field infrared microscopy allows us to directly image nanoscale metallic puddles that appear at the onset of the insulator-to-metal transition. In combination with far-field infrared spectroscopy, the data reveal the Mott transition with divergent quasi-particle mass in the metallic puddles. The experimental approach used sets the stage for investigations of charge dynamics on the nanoscale in other inhomogeneous correlated electron systems.
Qazilbash
M M
MM
Physics Department, University of California-San Diego, La Jolla, CA 92093, USA. mumtaz@physics.ucsd.edu
Brehm
M
M
Chae
Byung-Gyu
BG
Ho
P-C
PC
Andreev
G O
GO
Kim
Bong-Jun
BJ
Yun
Sun Jin
SJ
Balatsky
A V
AV
Maple
M B
MB
Keilmann
F
F
Kim
Hyun-Tak
HT
Basov
D N
DN