Magnetic Structure of CsCoCl₃

Neutron diffraction measurements were carried out on single crystals of CsCoCl 3 , a quasi-one-dimensional antiferromagnet of Ising-like spins, in the long range ordered region. The determined magnetic structure at 4.2 K is composed of antiferromagnetic stacking of ferrimagnetic c -plane with three sublattices as determined by Melamud et al. The spins are aligned along c -axis and were evaluated to be 3.11 µ B at 0 K by extrapolation. Unusual temperature dependence of magnetic reflection intensity was observed and interpreted as a partial disordering transition in which one of the three sublattices in a c -plane loses its magnetization above 13.5 K resulting in antiferromagnetic c -planes. This transition is discussed in connection with the antiferro-ferrimagnetic transition in the triangular Ising lattice. The critical exponent of the magnetization was found to be 0.34 around the Néel temperature 20.82 K.