AVS 45th International Symposium
    Surface Science Division Monday Sessions
       Session SS1-MoM

Paper SS1-MoM5
Electronic Structure of Sn/Ge(111) along the @sr@3 x @sr@3 to 3x3 Phase Transition

Monday, November 2, 1998, 9:40 am, Room 308

Session: Issues in Surface Electronic Structure
Presenter: M.C. Asensio, LURE and CSIC, France
Authors: J. Avila, LURE and CSIC, France
A. Mascaraque, Universidad Autonoma Madrid, Spain
G. LeLay, CRMC2-CNRS, France
E.G. Michel, Universidad Autonoma Madrid, Spain
M.C. Asensio, LURE and CSIC, France
Correspondent: Click to Email
The @sr@3 x @sr@3-Sn/Ge(111) structure undergoes a phase transition to a 3x3 phase at low temperature,@footnote 1@@footnote 2@ which has been interpreted as a charge-density-wave@footnote 1@ where electron localization gives rise to strong correlation effects.@footnote 2@ We report an angle-resolved photoemission investigation on the band structure and the Fermi vector of this interface along the phase transition. The electronic bands at room temperature exhibit a prominent surface state originated from Sn p@sub z@ orbitals, dispersing 0.3 eV with minima at K points. The Fermi vector obtained from these data is close to 0.3 Å@super -@@super 1@, much smaller that the calculated value.@footnote 1@ The surface state band splits at low temperature in two dispersing bands with strong 3x3 periodicity, at variance with previous data.@footnote 2@ The observation of these two bands correlates with the appearance of two components in the shallow Sn core levels. These data together with several other evidences support that the phase transition is of the order-disorder type. The mechanism driving the phase transition will be discussed in view of different theoretical models. @FootnoteText@ @footnote 1@J.M. Carpinelli et al, Phys.Rev.Lett. 79, 2859 (1997). @footnote 2@A. Goldoni and S. Modesti, Phys.Rev. Lett. 79, 3266 (1997).