A Mossbauer study of the interface in U/Fe multilayers

U/Fe multilayers were fabricated with the expectation that the magnetic anisotropy behaviour (perpendicular magnetization of the Fe layers) seen in analogous multilayers of Ce and Fe would occur also in these multilayers. This behaviour has not been observed and it is suspected that the reason is connected with the nature of the interfaces between the U and Fe layers. In this investigation Mossbauer spectra of a standard U/Fe multilayer are compared to those of samples that may reproduce the conditions of the interface. The results show that samples of co-sputtered U and Fe simulate reasonably well the interface spectra and that the non-magnetic Fe seen in this material would inhibit magnetism induced in the U layers via the adjacent Fe layers and hence explain the absence of the expected magnetic anisotropy in U/Fe multilayers.