Curie temperature of ultrathin films of fcc-cobalt epitaxially grown on atomically flat Cu(100) surfaces

Abstract

We have explored the relationship between epitaxial growth and magnetism in the case of ultrathin fcc-Co films by means of a multitechnique approach. For high-quality fcc-Co films less than 3 monolayers thick the Curie temperatures ${\mathrm{T}}_{\mathrm{C}}$ are dramatically lower than ${\mathrm{T}}_{\mathrm{C}}^{\mathrm{B}}$ of bulk fcc-Co and decease distinctly with film thickness. In contrast to previous claims, ${\mathrm{T}}_{\mathrm{C}}$ of a single monolayer appears to be far below 300 K. Substrate topology is found to strongly influence the structural perfection of the films which in turn determines their magnetic properties (Curie temperature, coercive field, and anisotropies).