Low-field AC susceptibility measurements on monocrystalline erbium

The magnetic properties of monocrystalline erbium have been determined with low-field AC susceptibility measurements between 4.2 and 150 K for different frequencies and magnetic fields with the applied field parallel and perpendicular to the c axis. The real component of the susceptibility shows anomalies at the antiferromagnetic transition (T N =85 K) and at the ferromagnetic transition (T C =19 K) as well as for the basal plane ordering transition at 52 K and for commensurate transitions at 34 and 28 K. The magnetic effects at these transitions are discussed in relation to the results of previous calorimetric measurements on the same crystal. To account for the observed non-zero value of the imaginary part of the susceptibility at the transitions, different loss mechanisms are suggested.