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W. Rupp, M. Schmid, P. Varga:
"Ion beam induced change of structural and magnetic properties of Fe on Cu(100)";
Poster: Symp. on Surface Science 2006 (3S'06), St. Christoph am Arlberg; 09.03.2006; in: "Contributions, 3S'06 Symposium on Surface Science 2006", F. Aumayr, P. Varga (Hrg.); (2006), S. 131 - 132.

For bulk iron it is well known that the γ-phase (i.e. face-centered cubic (fcc) phase which is paramagnetic) is stable only above 1184 K, whereas the body-centered cubic (bcc) α-phase (which is ferromagnetic) is thermodynamically stable only below this temperature. Ultrathin iron films are possible candidates for future magnetic recording media. For epitaxial iron films grown on Cu(100) it was believed that a fcc ferromagnetic Fe phase has been found [1, 2, 3]. We have shown that the fcc phase, which has no magnetic moment, can be achieved at room temperature (RT) only for a thickness of 5 to 10 monolayers (ML). Below that thickness (i.e. 2 - 5 ML) the structure turned out to be strained bcc (nanomartensite) [4, 5] with a magnetic moment perpendicular to the surface. Above 10 ML the film becomes fully relaxed bcc with an in-plane magnetic moment.

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