Visualization of the molecular Jahn-Teller effect in an insulating K4C60 monolayer.
We present a low-temperature scanning tunneling microscopy (STM) study of K(x)C60 monolayers on Au(111) for 3 < or = x < or = 4. The STM spectrum evolves from one that is characteristic of a metal at x = 3 to one that is characteristic of an insulator at x = 4. This electronic transition is accompanied by a dramatic structural rearrangement of the C60 molecules. The Jahn-Teller effect, a charge-induced mechanical deformation of molecular structure, is directly visualized in the K4C60 monolayer at the single-molecule level. These results, along with theoretical analyses, provide strong evidence that the transition from metal to insulator in K(x)C60 monolayers is caused by the Jahn-Teller effect.
Wachowiak
A
A
Department of Physics, University of California at Berkeley, Berkeley, CA 94720-7300, USA.
Yamachika
R
R
Khoo
K H
KH
Wang
Y
Y
Grobis
M
M
Lee
D-H
DH
Louie
Steven G
SG
Crommie
M F
MF