a1 Ames Laboratory, Iowa State University, Ames, Iowa, 50011
a2 Department of Chemistry, Iowa State University, Ames, Iowa 50011
a3 Department of Material Science and Engineering, Iowa State University, Ames, Iowa 50011
Based on X-ray photoelectron spectroscopy, Gd5Ge4(010) does not show evidence of surface segregation. Scanning tunneling microscopy reveals two types of terraces which alternate laterally on the surface. From the step heights, these two surface terminations are assigned as dense, Gd-pure layers in the bulk structure. There is evidence of reconstruction on one type of terrace.