Investigation of the structure of ultra-thin films of Fe on Cu(1Â 1Â 1) using medium-energy ion scattering

The structure of a 12 ML ultra-thin film of Fe on Cu(1 1 1) has been investigated using medium-energy ion scattering. The as-deposited film was found to be poorly ordered with a mean square static displacement of 0.23 Å However, the order was improved by post-deposition annealing using temperatures up to 250 °C, which reduced the mean square static displacement to 0.15 Å. The structure of the as-deposited film was consistent with a poorly ordered Kurjumov-Sachs coincidence-(1 1 1)fcc∥(1 1 0)bcc, [1¯10]fcc∥[1¯11]bcc, [112¯]fcc∥[1¯12¯]bcc-as reported by other workers, but with some evidence of coexistence of other orientations. Upon annealing the more-ordered film structure was dominated by the Greninger-Troiano orientation-(1 1 1)fcc ∼ 1° from (1 1 0)bcc, 〈1 1 2〉fcc ∼ 2° from [11¯0]bcc-with coexistence of both Kurjumov-Sachs and Nishiyama-Wassermann-(1 1 1)fcc∥(1 1 0)bcc, [1¯01]fcc∥[001]bcc, [1¯21¯]fcc∥[1¯10]bcc-coincidences.