Multilayer reconstruction of ultrathin epitaxial fcc Fe films

Abstract

We present a detailed structural analysis of a 4 monolayer fcc Fe film epitaxially grown at 300 K on Cu(100). Measurement (at 90 K) and full dynamical evaluation of low energy electron diffraction intensities shows that at low temperatures all layers are substantially reconstructed both in-plane and vertically. This corresponds to a very complex structure with 40 structural parameters to determine. The application of tensor-LEED leads to a convincing experiment-theory fit mirrored by a Pendry R-factor R = 0.14. No indications for the intermixing of iron and copper atoms are found. The film structure is characterized by an increased volume of iron atoms (V = 12.1 Å3) compared to that extrapolated from the high temperature equilibrium phase of fcc iron (V0 = 11.4 Å3). This is in line with ferromagnetism observed in all layers of the film.