Crystal Field Calculation of Principal Magnetic Susceptibilities and Anisotropy Variation with Temperature of Anhydrous Neodymium Chloride

In the temperature range 5 to 300°K, the principal susceptibilities of single crystals of anhydrous NdCl 3 have been calculated on the assumption that a single suitable trigonal field of C 3 h symmetry exists in the neighbourhood of the Nd 3+ ion. Furthermore the variation of magnetic anisotropy with temperature is studied and found to increase with the decrease of temperature. The g ‐values for the lowest level, viz., g ∥ = 4.103, g ⟂ = 1.746, compare well with the experimental values obtained from paramagnetic resonance absorption. The following crystal field parameters, reported by Judd, were used in these calculations: A   2 0 〈 r 2 〉 = 103.7 cm −1 , A   6 0 〈 r 6 〉 = −44.51 cm −1 , A   4 0 〈 r 4 〉 = −36.01 cm −1 , A 6 6 〈 r 6 〉 = 426.21 cm −1 .