Structure evolution of Ni ultrathin films on Pt(1 1 1)

Low-energy electron diffraction and Auger electron spectroscopy were used to study the initial growth and the alloy formation of Ni ultrathin films on Pt(1 1 1) surface. Several interesting structural phases were observed in this system: pseudo-(1×1), (3×3)R30°, coherent epitaxy, incoherent epitaxy, and (2×2). The phase diagram was determined by LEED. In addition, the formation of Ni–Pt alloy was investigated at various Ni coverages. The starting temperature for the alloy formation increases significantly as the Ni thin films turn into three-dimensional islands.