Magnetic interface formation at Cr/Fe(100) and Fe/Cr/Fe(100): Magnetic dichroism in photoemission study

The early stages of the growth of Cr/Fe(100) and Fe/Cr/Fe(100) interfaces have been investigated by magnetic dichroism in photoemission of Fe 3p and Cr 3p core levels as measured from chiral experiments employing linearly polarized synchrotron radiation. Evidence is obtained for a 30% larger magnetic moment of interface Cr atoms with respect to Cr atoms belonging to epitaxial ultrathin films and a 40% magnetic moment enhancement of top Fe interface atoms in the Fe/Cr/Fe(100) trilayer. The kinetic growth conditions (450 K) lead to a uniform overlayer growth, without intermixing, but dominated by islanding. As a consequence the formation of a single-surface ferromagnetic domain for Fe/Cr/Fe(100) is frustrated up to two Fe monolayer (ML) thickness. The line shape of Fe 3p photoemission in the frustrated regime is consistent with the presence of in-plane magnetic order at 90 degrees with respect to the substrate magnetization direction. The appearance of photoemission magnetic dichroism for Fe overlayer thicknesses exceeding 2 ML is interpreted as due to domain rotation towards the direction antiparallel to the Fe substrate magnetization.