title: Visualization of the molecular Jahn-Teller effect in an insulating K4C60 monolayer.
abstract: 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.
authors.affiliation: Department of Physics, University of California at Berkeley, Berkeley, CA 94720-7300, USA.
authors.forename: A
authors.initials: A
authors.lastname: Wachowiak
authors.forename: R
authors.initials: R
authors.lastname: Yamachika
authors.forename: K H
authors.initials: KH
authors.lastname: Khoo
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: M
authors.initials: M
authors.lastname: Grobis
authors.forename: D-H
authors.initials: DH
authors.lastname: Lee
authors.forename: Steven G
authors.initials: SG
authors.lastname: Louie
authors.forename: M F
authors.initials: MF
authors.lastname: Crommie