Observation of a Mott insulating ground state for Sn/Ge(111) at low temperature.
We report an investigation on the properties of 0.33 ML of Sn on Ge(111) at temperatures down to 5 K. Low-energy electron diffraction and scanning tunneling microscopy show that the (3x3) phase formed at approximately 200 K, reverts to a new ((square root 3)x(square root 3))R30 degrees phase below 30 K. The vertical distortion characteristic of the (3x3) phase is lost across the phase transition, which is fully reversible. Angle-resolved photoemission experiments show that, concomitantly with the structural phase transition, a metal-insulator phase transition takes place. The ((square root 3)x(square root 3))R30 degrees ground state is interpreted as the formation of a Mott insulator for a narrow half-filled band in a two-dimensional triangular lattice.
Cortés
R
R
Departamento de Física de Materiales, Universidad Complutense de Madrid, 28040 Madrid, Spain.
Tejeda
A
A
Lobo
J
J
Didiot
C
C
Kierren
B
B
Malterre
D
D
Michel
E G
EG
Mascaraque
A
A