Temperature-dependent order of clean Pd(110)

Abstract

We report high resolution low-energy-electron-diffraction measurements on the Pd(110) surface. We demonstrate that the clean surface consists of semiordered islands. The island structure is stable up to 650°C at which point the island edges roughen and step-step correlations decrease. Above 1100°C, surface evaporation becomes important and the surface becomes kinetically rough. A simple model is presented that makes use of step-step interactions to generate the periodic island structure. This model predicts that ordered islands form below the roughening temperature if the step creation energy is small compared to the step-step interaction. The existence of isolated steps is shown to be consistent with embedded atom calculations that predict a small step-formation energy on Pd(110) surfaces. © 1993 The American Physical Society.