Kang, S.-S., Kuch, W. and Kirschner, J.

A series of Fe thin films with thicknesses ranging from 1monolayer (ML) to 30 ML was deposited on a Cu90Au10(001) substrate (a = 3.66 Å ) at room temperature. Structural properties were investigated by low energy electron diffraction (LEED). From intensity vs energy [ I (E) ] measurements of the specular LEED reflection, three different structural phases were observed. The first phase at low Fe thicknesses (<4 ML) is a tetragonally expanded fcc phase (fct) with an interlayer distance a above 1.90 Å. The second phase at Fe thicknesses between 4 and 10 ML is associated with an interlayer distance a 1.76 Å. With further increasing Fe thickness (> 10 ML), the third phase, a bcc(011) structure with a 2.03 Å, occurs. The magnetic properties were studied by in situ magneto-optical Kerr effect (MOKE). It was found that the Fe films of the first and third phase have a high-spin ferromagnetic moment, while they exhibit a low net magnetic moment in the second phase. The observed structural and magnetic phases are thus similar to the Fe/Cu(001) system. The direction of the easy magnetic axis in Fe/Cu90Au10 is perpendicular to the film plane only at thicknesses below 2 ML, where structural and magnetic a spin reorientation transition from perpendicular to the film plane to in-plane with increasing film thickness has been found. The origin of perpendicular magnetization is discussed.

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