The two-component non-collinear antiferromagnetic structures of DyNiC 2 and HoNiC 2

Abstract

DyNiC 2 and HoNiC 2, which crystallize in the orthorhombic space group Amm2, have been studied by neutron powder diffraction in the temperature range from 300 to 1.9 K. Both compounds exhibit modulated antiferromagnetic configurations of the rare earth magnetic moments. The magnetic transition temperatures are 10 and 4 K for DyNiC 2 and HoNiC 2, respectively. The magnetic structures are described by two propagation vectors: the commensurate k 1=[0, 0, 1] and the incommensurate k 2=[ 1 2 −τ, 1 3 +τ, k z ] with τ=0.03 and 0 and k z =0.935 and 0.86 for DyNiC 2 and HoNiC 2 respectively. The magnitude and direction of the magnetic moments are determined. The resultant non-collinear antiferromagnetic spin configurations are discussed with respect to crystal field and magnetic exchange interactions.