Evolution of magnetic layers stacking sequence within the magnetic structure of Ho(CoxNi1−x)2B2C

We evaluated the influence of Co substitution on the magnetic structure of Ho(CoxNi1−x)2B2C (x=0.2, 0.4, 0.6, 0.8) using neutron diffraction, magnetization and specific heat studies. Different modes are stabilized: an AFM k→x=0.2=(0,0,1) mode for x=0.2, a spiral k→x=0.4=(0,0,0.49) mode for x=0.4, a spiral k→x=0.6=(0,0,0.26) mode for x=0.6, and a FM k→x=0.8=(0,0,0) mode for x=0.8. Recalling that for x=0.0, k→x=0=(0,0,1) while for x=1.0, k→x=1.0=(0,0,0), then all these magnetic structures can be visualized as a variation in the stacking sequence, along the z-axis, of the intra-planar FM-coupled Ho sheets as such Co substitution controls the z-component of the k→x=(0,0,ux) vector where ux=0,0.26,0.49, or 1. We discuss this inference and the observation that in spite of such a diversity of magnetic structures, the critical temperatures and the saturated moments are only weakly influenced by substitution.