Rumpled surface structure and lattice dynamics of NiO(001)

Abstract

Rumpled surface structure and root mean square (rms) thermal vibration amplitudes of NiO(001) were determined by high-resolution medium energy ion scattering. The clean 1\ifmmode\times\else\texttimes\fi{}1 surface was prepared by cleavage in the air and annealing at 500 \ifmmode^\circ\else\textdegree\fi{}C for 40 min in ${\mathrm{O}}_{2}$ pressure of $1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ Torr. The interlayer distance between the top and second layer is contracted by 1.44\ifmmode\pm\else\textpm\fi{}0.07% and the top-layer Ni plane is displaced by 0.10\ifmmode\pm\else\textpm\fi{}0.01 \AA{} toward the vacuum side relative to the top-layer O plane. The present result is consistent with the recent ab initio calculation based on the density functional theory using the local spin density approximation. We also determined the rms thermal vibration amplitudes of Ni and O atoms in the bulk and in the top layer. The result obtained is compared with that calculated using the pair potential proposed by Lewis and Catlow.