MAGNETIC AND MAGNETOTRANSPORT OF AMORPHOUS U-AS FILMS

Amorphous thin films of UxAs100-x are ferromagnetic for U-rich compositions, 49 less-than-or-equal-to x less-than-or-equal-to 75, with a magnetic moment of 0.2 to 0.4-mu-B per U atom and Curie temperatures, T(c), 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 T(c), the anomalous Hall angle is theta-H = 12-degrees and the anomalous Hall coefficient is R(S) almost-equal-to 10(-7) OMEGA cm/G. Maximum polar Kerr rotation for U62As38 is -2.0-degrees 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.