Preparation dependent surface structure of NiAl(100)

The dependence of surface structure formation on preparation conditions of NiAl(100) has been investigated by Scanning Tunnelling Microscopy (STM), Low Energy Electron Diffraction (LEED) and Density Functional Theory (DFT). STM and LEED have been used to study the surface after sputtering, low temperature annealing (T<500K) and high temperature annealing (500K<T<1000K). A (1×1) phase is observed both after sputtering and low T annealing, with STM images indicating the formation of row structures - the density of which appears dependent on annealing time. ${\rm{A c(}}\sqrt 2 \times 3\sqrt 2 ){\rm{R}}45^\circ$ regime is detected upon higher T annealing - forming two, orthogonal, row-based domains. STM simulation produced using DFT explains the origin of one of the domains - a defect based structure with a dominant Ni density of states contribution.