Structural Investigation of the BaFe$_{2}$As$_{2}$(001) Surface Using LEED and STM*

BaFe$_{2}$As$_{2}$, a parent compound to one of the newly discovered high-$T_{c}$ superconductors, presents very interesting physical properties such as a structural transition occurring prior to the formation of a spin density wave. It is surely of interest to investigate the effect of breaking the symmetry by creating a surface. Single crystals of BaFe$_{2}$As$_{2 }$were cleaved in vacuum exposing a (001) surface. Quantitative LEED I-V measurements and low-temperature STM topography revealed an ordered As surface with disorded Ba atoms present. LEED shows a clear (1 $\times $ 1) periodicity with a surface structure slightly different than the bulk. STM reveals a weak C(2 $\times $ 2) periodicity. We will explore the possibility that the C(2x2) STM image is electronic in origin.