Growth and structure of Fe on MgO(0 0 1) studied by modulated electron emission

Fe films 10 monolayers thick were prepared in ultrahigh vacuum by thermal deposition on in-air cleaved MgO(0 0 1) substrate held at room temperature and 500 °C. Auger electron spectroscopy, low energy electron diffraction, and scattering-interference of primary and backscattered electrons were used to investigate the growth mode and the structure of the film. The room temperature deposition results in a nearly continuous (90% fractional coverage) body-centred-tetragonal film with the Fe[0 0 1]∥MgO[0 0 1] and Fe〈1 0 0〉∥MgO〈1 1 0〉 orientation relationships. Film annealing at 300 °C increases the quality of the film. In-plane expansion of +2.4% and out-of-plane contraction of −3.2% of the Fe cubic cell has been determined. A complete removal of the tetragonal distortion and a strong islanding (35% fractional coverage) occur for annealing temperature of 500 °C. Film deposition at 500 °C substrate temperature leads to body centred Fe islands that cover about 55% of the substrate.