Magnetic ordering of ultrathin Mn films on Fe(100) studied via capture of polarized electrons by fast ions

The magnetic ordering of the topmost surface layer of Mn films grown on Fe(100) at different temperatures is investigated via the polarization of fluorescence light emitted after capture of spin-polarized electrons into excited atomic terms during scattering of 25-keV ${\mathrm{He}}^{+}$ ions. For coverages up to about 0.5 ML the observed spin polarization is in accordance with in-plane ferromagnetic order of Mn moments with antiparallel coupling to moments of the Fe substrate. For 1–8-ML films the detected spin polarization vanishes, indicating in-plane antiferromagnetic order of the topmost layer.