Structure and Magnetism of Thin UX Layers

Abstract

US layers (thickness 0.1 0.3 m) were prepared by sputter deposition from US target in Ar atmosphere at temperatures 298 573 K. For US thin films, magnetism tends to be suppressed comparing to the bulk US, which is a band ferromagnet with TC = 177 K. TC decreases down to 85 105K for the layers deposited at room temperature (depending on the deposition parameters) and increases with the increase of the temperature of substrate. Spontaneous magnetization in the ordered state is suppressed considerably for the deposited layers: down to 0.1B/f.u. or less for all samples studied (compare with 1.55 B/f.u. for bulk US). The changes in the magnetic properties are correlated with the microstructure of the films. Microstructure studies indicated that the US thin films contain a mixture of “nanocrystalline” and “amorphous” parts. The crystallite size in the nanocrystalline parts is approximately 100 A . In all samples, a compressive residual stress was observed, which caused a strongly anisotropic lattice deformation with the easy deformation direction (1 1 1). The compressive residual stress was below −3GPa in most samples. Results are compared with UN layers synthesized by reactive sputtering.JRC.E.6-Actinides researc