Importance of higher order terms in CF Hamiltonian for interpretation of magnetization curves in Tb(Cu 0.7Ni 0.3) 2

Abstract

The crystal field (CF) contribution to the magnetic field dependence of the magnetization in the ferromagnetic compound Tb(Cu 0.7N 0.3) 2 has been analysed theoretically. Contrary to the susceptibility data, the step-like appearance in the magnetization curves along the b axis cannot be explained in terms of second order in orthorhombic CF Hamiltonian only. It is shown, that to account for all features of the magnetization data in fields up to 24 T, the higher order terms should be included into the CF Hamiltonian.