Crystal-field effects in the high-field magnetization of polycrystallinePrNi5

The induced magnetic moment of polycrystalline ${\mathrm{PrNi}}_5$ was investigated at T=4.2 K in magnetic fields up to 40 T. The magnetization increases faster than linear in magnetic fields less than 14 T, which is believed to be a result of a level crossing induced by the magnetic field. The observed magnetization compares well with the induced magnetic moment, calculated on the basis of a molecular-field Hamiltonian, which includes the crystalline electric field potential, Zeeman term, and isotropic exchange interactions. The calculations indicate that at lower temperatures the level crossing would give a stepwise increase of the magnetization, which is expected to be between 15 and 19 T, depending on the crystal-field level scheme. At 4.2 K the transition is smeared out and should be very sharp if the temperature is lowered below 1 K.