Magnetic and magnetotransport of amorphous U-As films

Amorphous thin films of UxAs100-x are ferromagnetic for U-rich compositions, 49≤x≤75, with a magnetic moment of 0.2 to 0.4 μB per U atom and Curie temperatures, Tc, up to 120 K. Large resistivities are found at 5 K for compositions x<51, indicating semiconducting properties for low U content. For the highest Tc, the anomalous Hall angle is θH = 12° and the anomalous Hall coefficient is RS ≊ 10-7 Ω cm/G. Maximum polar Kerr rotation for U62As38 is -2.0° at 1-eV photon energy. The properties of U-As amorphous films are similar in many respects to those of amorphous U-Sb, except that the maximum values of these properties occur at higher U contents. The results are discussed in terms of spin-orbit interactions.