Kerr rotation measurements on amorphous U-As-Co thin films

Thin films of (U-As)100-xCox alloys are prepared by magnetron sputtering over the entire composition range x and the polar Kerr rotation and magnetization are measured. The absolute value of the maximum Kerr rotation decreases rapidly from -0.48° for Co (x=100) to -0.09° for x=66 at 300 K. A similar decrease is observed at 10 K but at a slightly slower rate. The Kerr rotation as well as the magnetization are negligible at x≅50, indicating a suppression of the magnetic moments in Co and U, simultaneously. This result is explained in terms of filling in the Co 3d conduction band. At x≤30, U develops a magnetic moment at 10 K but Co does not seem to contribute to the magnetization for these compositions.