Magnetic anisotropy and spin reorientation in U2Co15Si2

Abstract Field and temperature dependencies of the magnetization measured along the principal axes of a U 2 Co 15 Si 2 single crystal show that this compound is a ferromagnet with a spontaneous magnetic moment of 14.8 μ B per formula unit (at 4.2 K), located in the basal plane of the hexagonal crystal structure. A strong easy-plane magnetic anisotropy ( K 1 =−0.97 MJ m −3 at 4.2 K) is attributed to the U sublattice because Lu 2 Co 15 Si 2 exhibits easy-axis anisotropy with K 1 =0.42 MJ m −3 . The easy-plane anisotropy of U 2 Co 15 Si 2 transforms to a cone of easy axes above 270 K. The magnetization vector approaches the c -axis at 350 K, and the compound has easy c -axis anisotropy up to the Curie temperature T C =601 K.