Surface Rumpling of MgO(001) Deduced from Changes in RHEED Kikuchi Pattern. I. Experimental

Abstract

Vacuum-cleaved MgO(001) surface has been studied by reflection high energy electron diffraction (RHEED). With specimens heated to 300°C and gradually cooled anomalous enhancement of Kikuchi pattern is observed in the [100] azimuth at glancing angle 3.5°, which is unobservable with as-cleaved specimens. The appearance of such pattern is attributed to differential relaxation of surface anions and cations, or surface rumpling, that has occurred during the annealing. From the values of glancing angle given above, the magnitude of rumpling is estimated at 6% of the normal atomic spacing.