Magnetism of uranium/iron multilayers: I. Fabrication and characterization

U/Fe multilayers constitute a magnetic system in which the 3d magnetism of the Fe layers will be modified by hybridization with the U 5f electrons. This paper describes a programme of measurements of the magnetic behaviour of these systems beginning with the fabrication and thorough characterization of the samples. Metallic U/Fe multilayers were prepared by DC sputtering in a UHV chamber. A range of samples with measured U thicknesses, tU, in the range 18–66 A and Fe thicknesses, tFe, from 7 to 108 A was fabricated. X-ray and neutron reflectivity measurements showed strong peaks indicating good layer structure and gave a determination of the bilayer thickness. X-ray diffraction analysis showed crystalline α-U and α-Fe for layer thicknesses greater than about 20 A. The α-Fe is strongly textured with (110) planes in the layer plane. The Fe lattice parameter is larger for the case of thin layers, but approaches the bulk value of 2.866 A at tFe ~ 75 A. Mossbauer spectra of α-Fe were obtained for tFe ≥ 18 A; a non-magnetic component of thickness ~ 12 A per layer is always present. The results from these different experimental techniques are combined to present a detailed description of these multilayer systems.