Growth and structural transition of Fe ultrathin films on Ni(111) investigated by LEED and STM

Abstract

The growth of Fe ultrathin films on Ni(111) at room temperature has been investigated by low-energy electron diffraction and scanning tunneling microscopy. In the initial deposition, a pseudomorphic fcc-Fe(111) monolayer with triangular line defects grows on the Ni substrate. Triangular lines consist of atomic-size dark spots located in the Ni atom sites and are interpreted in terms of the misfit-induced atomic vacancies in the Ni substrate. With further deposition, the second monolayer Fe film, which consists of three elongated domains of a striped structure, grows on the first monolayer fcc-Fe film. The striped structure results from the growth of a distorted bcc-Fe(110) phase with one-dimensional Nishiyama-Wassermann orientation. Further deposition leads to the growth of thicker bcc (110) films on the distorted bcc(110) domains, forming three-dimensional ridgelike islands. The first and second monolayer Fe films grow in an incomplete layer-by-layer growth mode and the thicker Fe films grow in a three-dimensional island growth mode.