Structure and magnetic properties of Ru/Fe(001) multilayers

The structure and magnetic properties of Fe/Ru(001) multilayers are studied using x-ray diffraction, magneto-optical Kerr-effect magnetometry, and x-ray magnetic circular dichroism. The Fe layer thickness is maintained constant at 7.5 Å, while the nominal Ru layer thickness $t_{\mathrm{Ru}}$ is variable. For $t_{\mathrm{Ru}}<3.5\mathrm{}$ Å, the multilayer has a body-centered-tetragonal structure with a perpendicular lattice constant that varies linearly with Ru thickness. In this region, the Fe has a bulklike magnetic moment. The Ru has a monotonically decreasing moment with increasing thickness. The Ru moments are of order $0.5{\mu }_B$ in this region. Beyond $t_{\mathrm{Ru}}\approx 3.5\hspace{0.5em}\mathrm{\AA },$ the crystal structure of the multilayer transforms to an hcp (102) orientation and the magnetic moments of both the Fe and Ru disappear. These results are compared and contrasted with those from Fe/Rh(001) multilayers.