The zero-field splitting anomaly of Gd3+ in LaEtSO4

Comparison has been made between the predictions of the zero-field splitting resulting from spin Hamiltonians which fit the paramagnetic resonance spectra of Gd 3+ in LaEtSO 4 at a number of temperatures between 4·2 °K and 285 °K, and direct measurements of these splittings. It is shown that the spin Hamiltonian represents the system to an accuracy of better than 0·3% from magnetic fields from 4500 G down to and including zero field.