Structural analysis of one-dimensional atomic chain on Pt/Ge(001) surface by reflection high-energy positron diffraction

Mochizuki, Izumi; Fukaya, Yuki   ; Kawasuso, Atsuo

Quasi one dimensional (1D) metallic chain of single-atom wide is constructed on the Ge(001) surface by the adsorption of Pt atoms. While the 1D chain is required the elucidation of the electronic properties about the 1D metal or the metal-insulator transition, there is also discussed about the atomic arrangement. The recent results by first-principle calculation suggest the atomic chain is configured by the Ge dimers that so far was admitted that by the Pt dimers, and that is still to be determined. We have measured the reflection high energy positron diffraction (RHEPD) to elucidate the atomic arrangement of the 1D chain. The obtained RHEPD rocking curve does not match the dynamical calculation assuming the Pt dimers, on the other hand that of the Ge dimers is able to reproduce the curve generally better. Although there are needs to optimize the parameters such as atomic positions or Debye temperatures, the RHEPD results show the 1D chain on the Pt/Ge(001) surface is the Ge dimers.