Low temperature specific heats of erbium dihydrine. Magnetic transition and crystal field splitting effects

The specific heat of erbium dihydride, ErH_1.99, was measured in the temperature range from 1.8–230 K. A λ-type specific heat anomaly, most probably due to an antiferrómagnetic transition has been found at T_N = 2.13 ± 0.03 K. The influence of the crystal field of cubic symmetry on the splitting of the ground state ⁴I_{$\text{15}\text{2}$} of the Er³⁺ ion was analysed and the conclusion was drawn, that the doublet Γ₇ is the lowest lying crystal-field level.