Oxygen adsorption on Co(101¯0): Different reconstruction behavior of hcp (101¯0) and fcc(110)

Abstract

Co(101\ifmmode\bar\else\textasciimacron\fi{}0) with close-packed rows separated by the c-axis distance in a hcp analog to fcc (110). In contrast to the (2\ifmmode\times\else\texttimes\fi{}1) missing-row (MR) structures formed upon oxygen adsorption on several fcc (110) surfaces, a novel type of MR reconstruction is revealed by scanning tunnel microscopy and low energy electron diffraction on Co(101\ifmmode\bar\else\textasciimacron\fi{}0): The low coverage (2\ifmmode\times\else\texttimes\fi{}1) O phase constitutes a double-layer MR structure with (2\ifmmode\times\else\texttimes\fi{}1) MR configurations in the two topmost Co layers; it develops locally by moving every other atom at the topmost close-packed Co rows into respective short bridge sites of the layer underneath. Results on the c(2\ifmmode\times\else\texttimes\fi{}4) and the high coverage (2\ifmmode\times\else\texttimes\fi{}1) oxygen phases support this conclusion.