Novel orientational ordering and reentrant metallicity in K(x)C(60) monolayers for 3 < or = x < or = 5.
STM studies on K(x)C(60) monolayers reveal new behavior over a wide range of the phase diagram. As x increases from 3 to 5 K(x)C(60) monolayers undergo metal-insulator-metal reentrant phase transitions and exhibit a variety of novel orientational orderings, including a complex 7-molecule, pinwheel-like structure. The proposed driving mechanism for the orientational ordering is the lowering of electron kinetic energy by maximizing the overlap of neighboring molecular orbitals. In insulating (metallic) K(x)C(60) this gives rise to orbital versions of the superexchange (double-exchange) interaction.
Wang
Yayu
Y
Department of Physics, University of California at Berkeley, and Materials Sciences Division, Lawrence Berkeley Laboratory, Berkeley, CA 94720-7300, USA.
Yamachika
R
R
Wachowiak
A
A
Grobis
M
M
Khoo
K H
KH
Lee
D-H
DH
Louie
Steven G
SG
Crommie
M F
MF
D004583:Electrons; D008670:Metals / Q000737:chemistry; D028561:Transition Elements
D008670:Metals; D028561:Transition Elements