Linear Antiferromagnetic Chains in Hexagonal ABCl3-Type Compounds (A; Cs, or Rb, B; Cu, Ni, Co, or Fe)

Magnetic properties of single crystal of CsCuCl 3 , CsNiCl 3 , RbNiCl 3 , CsCoCl 3 , and RbFeCl 3 were investigated by the measurements of magnetic susceptibilities, magnetic torques, ESR absorptions from liquid helium temperature to room temperature. The experimental results were interpreted in terms of linear antiferromagnetic chains, taking into account the effect of crystal field. The anisotropic exchange interaction energies between the neighboring magnetic inos along a chain were estimated to be J // / k =-7.0°K, -11.0°K, -14.1°K, -85°K, and -11.5°K, and J ⊥ / k =-6.0°K, -11.0°K, -14.1°K, -17.0°K, and -3.8°K, for CsCuCl 3 , CsNiCl 3 , RbNiCl 3 , CsCoCl 3 , and RbFeCl 3 , respectively by the comparison with the calculated susceptibilities for linear antiferromagnetic chains with Heisenberg and Ising spins by Bonner, Fisher et al. . Properties which appeared in short range magnetic order were studied for two nickelous compounds above T N , 4.5°K in CsNiCl 3 and 11°K in RbNiCl 3 . A qualitative discussion of the exchange interaction in these compounds is given.