Magnetic structure determination of NdNiC2 and TmNiC2 by neutron diffraction

Isostructural orthorhombic NdNiC₂ and TmNiC₂ reveal collinear antiferromagnetic structures with magnetic propagation vectors [1/21/20] and [0, 0, 1], respectively. In NdNiC₂, ferromagnetic (110) planes are coupled pairwise in opposite spin orientations; in TmNiC₂, adjacent ferromagnetic (001) planes are coupled antiferromagnetically. The magnetic moments are oriented parallel to the a-axis and have values of 2.7μ_B (Nd) and 3.3μ_B (Tm) at 4 K.     

Neutronenbeugungsuntersuchungen der magnetischen Struktur von TmCo3

The magnetic structure of the intermetallic TmCo₃ compound, determined by neutron diffraction measurements at 4.2 K on a powder sample, is colinear to the hexagonal c-axis, with the magnetic moments of Tm- and Co-ions being antiparallel coupled. The saturation moments have been found to beµ(Tm)=6.5µ _B andµ(Co)=0.8µ _B . The calculated magnetic moment of the Tm-ion by crystal field theory, based on a point charge model, is that of the free Tm³⁺ ion.     

Field-induced magnetic transition in CrCo3

The action of a magnetic field on a single crystal of the compound ErCo₃ has been investigated by both magnetization and neutron diffraction measurements. ErCo₃ is ferrimagnetic with an easy magnetization axis parallel to the c axis of the crystal. When the field is applied perpendicular to the c axis a transition occurs: the moment of one of the two Er sites remains nearly oriented along the c axis while this of the other Er site rotates through an angle of 55°. From the value of the threshold field, the difference between the anisotropy energies of the two sites has been evaluated.