ULTRATHIN METAL FILMS BY DESIGN: EXPLOITING THE CLOSE CORRELATION BETWEEN STRUCTURE AND MAGNETISM

Abstract

To design ultrathin metal films with desired properties, it is necessary to understand the close correlation between film structure and film properties. In this paper several examples of the relationship between the magnetism and the structure of thin metallic films are presented. It is demonstrated that for iron films on Cu(100) and Cu 3 Au (100) and for MnCu surface alloys, unusual film structures are often accompanied by unusual magnetic properties. While two fcc phases, which differ in their crystallographic and magnetic states, have been stabilized on Cu(100) depending upon film thickness, no fcc modification is observed on Cu 3 Au (100). This can be understood qualitatively if the different contributions to the total energy of the film are considered. For the weak magnets Mn and Fe studied here, this points towards a pronounced contribution of the surface to stabilizing unusual magnetic phases. This is demonstrated even quantitatively for the Cu (100) c(2×2) Mn phase, where an unusual surface-layer corrugation is accompanied by a large magnetic moment. An improved understanding of the energies that govern the correlation between structural and magnetic properties should widen the opportunities for designing ultrathin films with desired magnetic characteristics.