The structural and magnetic properties of ${\mathrm{Fe}}_x{\mathrm{Mn}}_{100-x}$ single and $\mathrm{Co}∕{\mathrm{Fe}}_x{\mathrm{Mn}}_{100-x}$ bilayers have been investigated by grazing ion scattering, Auger electron spectroscopy, low energy electron diffraction, and magneto-optical Kerr effect. The increase in coercivity of the Co hysteresis loops is used as a measure of the magnetic interface coupling in the bilayers. For FeMn films of 4 ML (monolayers), the onset of coupling is still detectable for temperatures below $160\mathrm{K}$. The strength of the coupling rapidly increases with increasing FeMn thickness. At 8 ML FeMn, appreciable interaction is observed at room temperature. For further increasing FeMn thickness, the Co films reveal a significant difference in the behavior of surface and bulk magnetizations.

• Received 14 May 2007

DOI:https://doi.org/10.1103/PhysRevB.76.224405