Anomalous behavior of LEED beam intensity during annealing

Low-energy electron diffraction was used to study the annealing effects of 1 ML Ag on the ultra-thin-film Co/Pt (111). The behavior of the specular beam intensity versus temperature is anomalous. Besides the normal Debye-Waller effect, a bend occurs at 550 K, and a dramatic increase occurs at a higher temperature. A corresponding study by Auger electron spectroscopy and ultraviolet photoelectron spectroscopy indicates that the bend results from the Co inter-diffusion. The anomalous increase indicates that a more stable state forms at a higher temperature. The Co coverage plays an important role in determining the turning temperature. Possible mechanisms are discussed.