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

Abstract 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 , u x ) vector where u x = 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.