Crystal structure and magnetic properties of Lu2Co17−xSix single crystals

Single crystals of Lu2Co17−xSix within the homogeneity range of Si substitution for Co (0 ≤ x ≤ 3.4) were grown by the Czochralski method. Magnetization measurements have revealed that the parent Lu2Co17 compound has a spin-reorientation transition (SRT) from the easy-plane to the easy-axis at elevated temperatures which occurs as 2 second-order phase transitions, the “plane-cone” at TSR1 ≈ 670 K and the “cone-axis” at TSR2 ≈ 730 K. The effect of Si substitution for Co on magnetic anisotropy and spin-reorientations of Lu2Co17 was studied. In Lu2Co16Si, the SRTs shift towards lower temperatures (TSR1 ≈ 75 K, TSR2 ≈ 130 K) and disappear for compounds with Si content x > 1 where the anisotropy is uniaxial over the whole range of magnetic ordering. A phenomenological discussion of Co sublattice anisotropy, with reference to the model of individual site contribution to magnetic anisotropy (ISA) is provided.