The Ground State in Cs₂KFe(CN)₆ From Single-Crystal Magnetic Properties

Abstract

The single-crystal magnetic susceptibilities from 4.5 to 300 K, and the magnetizations at 4.5 K from 0.25 to 5 T, of Cs₂KFe(CN)₆ along a, b and c* are reported. The data are fitted well by a crystal field model with splitting of the ground-state ²T_2g term of the hexacyanoferrate (III) ion. The three variable parameters of the model were the two representing the low-symmetry splitting of the t_2g orbitals, and the effective reduction in the orbital angular momentum. Four other parameters were fixed at values known or estimated from other experiments on hexacyanoferrate (III) ions, including polarized neutron diffraction which determines the orientation of lower-symmetry crystal field components. The crystal field has only inversion symmetry with respect to the ligand axes, with a non-cubic component which is almost uniaxial with respect to the a,b,c * axis system.