Theoretical study of surface alloy formation through generation and annihilation of vacancies

Abstract

Recent STM experiments suggest that the formation of a surface alloy, when Mn is deposited on Cu(100), could be attributed to a kink-induced vacancy formation, followed by Mn incorporation through vacancy annihilation in the step vicinity. We present an extension of the kinetic tight-binding Ising model, which takes into account the preferential formation of vacancies at the kink, their diffusion towards the centre of the terrace and their annihilation by Mn adatoms. The jump frequencies are obtained using molecular dynamics within the second moment approximation of the tight-binding scheme. The spatial distribution of incorporated Mn and its asymmetry between the upper and lower terrace are discussed in view of the STM experiments.