The magnetic properties of Fe x Mn 1Ϫx /Ir(001) superlattices ͑SL's͒ have been studied using linearly polarized soft x-ray resonant magnetic reflectivity ͑XRMS͒ at the Fe L 2,3 absorption edges. Previous superconducting quantum interference device magnetometry measurements have shown that the SL's exhibit a ferromagnetic behavior for xϾ0.75 and a nonmagnetic or antiferromagnetic one for xϽ0.75. XRMS measurements were performed on two SL's with compositions on each side of xϭ0.75, as well as on a thin layer of Fe-rich alloy (xϭ0.9). The Fe magnetic moments in these alloys were determined by comparing experimental and calculated energy-dependent asymmetry ratios at different angles in the reflectivity curves. Fe atoms are found in a high-spin ferromagnetic state for xϭ0.9, while they are in a low-spin ferromagnetic state for xϭ0.7. Our results emphasize the role of the tetragonalization parameter c/a on the occurrence of the different magnetic states. Measurements, at the Mn L 2,3 edges in a bct Fe 0.9 Mn 0.1 ultrathin layer reveal a net magnetic moment per Mn atom of about 1.7 B coupled antiparallel to the Fe one. ͓S0163-1829͑99͒03933-8͔

The surface of the AlPdMn quasicrystal perpendicular to a fivefold axis has been probed by LEED, XPS, Auger spectroscopy and surface EXAFS.