MAGNETIC INTERACTIONS IN CEBR3

Adiabatic susceptibility measurements have been performed on CeBr 3 in the helium range between 3.4 and 22.0 MHz. From the measurements we deduce the specific heat at constant magnetization CM / R≅ (0.0274±0.0011) / T2+(0.009±0.005) / T3 and an antiferromagnetic Curie-Weiss constant θ (sphere) = -0.050±0.045°K. These values are combined with the results of EPR spectra to give estimates of the diagonal terms of the nearest- and next-nearest-neighbors interaction tensors for Ce3+ ions in CeBr 3 which are compared with those found for CeCl3. The interaction tensors for the effective spins are found to contain terms which arise from high-degree superexchange of the form J+5(1) J-5(2) acting between the real spins. An analysis of the interactions indicates that CeBr3 should correspond well to a weakly perturbed linear chain system with either antiferromagnetic Ising or ferromagnetic XY interactions within the chain. © 1969 The American Institute of Physics.