Anatoli V. Melechko

Role of defects in two-dimensional phase transitions: An STM study of the Sn/Ge(111) system

A. V. Melechko, J. Braun, H. H. Weitering, and E. W. Plummer  

Physical Review B, 2000. 61(3): p. 2235-2245.



The influence of Ge substitutional defects and vacancies on the (sqrt[3] x sqrt[3])-->(3 x 3) charge-density wave phase transition in the alpha phase of Sn on Ge(111) has been studied using a variable-temperature scanning tunneling microscope. Above 105 K, Ge substitutional defects stabilize regions with (3 x 3) symmetry that grow with decreasing temperature and can be described by a superposition of exponentially damped waves. At low temperatures, T <~ 105 K defect-defect density-wave-mediated interactions force an alignment of the defects onto a honeycomb sublattice that supports the low-temperature (3 x 3) phase. This defect-mediated phase transition is completely reversible. The length scales involved in this defect-defect interaction dictate the domain size ( ~ 104 Å 2).

©2000 The American Physical Society

DOI: 10.1103/PhysRevB.61.2235
PACS: 68.35.Rh, 68.35.Bs, 71.45.Lr, 72.10.Fk


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