Crystal fields and magnetic properties of ErH3

Magnetization and magnetic susceptibility measurements have been made in the temperature range 1.3--4.2 K on powdered samples of ErH3. The susceptibility exhibits Curie--Weiss behavior from 4.2 K to 2 K, and intercepts the negative temperature axis at theta=1.05 +- 0.05 K, indicating that the material is antiferromagnetic. The low field effective moment is 6.77 +- 0.27 Bohr magnetons per ion. The magnetization exhibits a temperature independent contribution, the slope of which is (5 +- 1.2) x 10-6 Weber m/kg T. The saturation moment is 3.84 +- 0.15 Bohr magnetons per ion. The results can be qualitatively explained by the effects of crystal fields on the magnetic ions. Using the wave functions and energy level diagrams of Segal and Wallace (Ref. 4), the first excited state is estimated to be 95 K above the ground state