Crystalline electric field effects in the magnetic properties of hexagonal praseodymium compounds

Abstract

The high field magnetization and the magnetic susceptibility of hexagonal praseodymium compounds are calculated on the basis of a molecular field Hamiltonian, including the CEF potential, a Zeeman term, and isotropic exchange interactions. At low temperatures it is shown that the full magnetic moment of the Pr³⁺ ion is always reached in a stepwise manner for a magnetic field applied along the c-axis. Perpendicular to the c-axis this occurs only in the case of a Γ₄ ground state. This is a pure CEF effect, resulting from the crossing of the ground state by an excited state with a higher magnetic moment. The temperature dependence of the magnetic susceptibility would have a maximum corresponding to an appreciable population of an excited state with a greater magnetic moment. Some hexagonal Pr compounds are considered in which the discussed effects are or should be observable.