Anisotropy in Fe layers investigated by ferromagnetic resonance

Ferromagnetic resonance (FMR) is performed together with superconducting qu antum interference device and Faraday magnetometry to investigate the magne tic anisotropy of epitaxial bcc Fe(001) films on Ag(001) and Cr(001). The F e/Ag(001) and Fe/Cr(001) layers as well as corresponding wedge structures w ere grown by molecular-beam epitaxy. On these samples the following investi gations were done. Firstly the temperature dependence of the surface anisot ropy of the Fe/Ag system was determined. To achieve high precise values of the surface anisotropy a locally resolved FMR technique was applied to an F e wedge film coated in Ag layers. Secondly the influence of strong deformat ion of the Fe layer on the magnetic properties was investigated by high-dos e Fe-ion implantation in thermally immiscible Fe/Ag(001) layer structures. FMR measurements have shown a pronounced tetragonal symmetry of the anisotr opy, which can be precisely controlled by implantation conditions. Thirdly in Fe/Cr single-crystal layers the magnetic parameters of the Fe films show an anomalous temperature behaviour for a distinct Cr thickness range that can be related to the spin-flip transition. The transition temperature decr eases continuously with decreasing Cr thickness, ceasing in a suppression o f the spin flip for Cr thicknesses below 60 Angstrom. Below the transition temperature an increase in the dynamic contribution to the FMR linewidth oc curs which depends on the Cr thickness. The temperature variation in the dy namic line broadening is explained by a band theoretical description which agrees qualitatively with the temperature variation in the magnetic Fe mome nt.