Magnetism of ErNi2B2C investigated with a two-ion model for rare-earth antiferromagnets Original Research Article

A two-ion model for rare-earth antiferromagnets was employed in the present work to study the magnetic and thermodynamic properties of ErNi2B2C, and derive an analytic formula for the Néel temperature of the compound with the quantum perturbation theory. To apply the theory, four new base functions had to be composed due to the special forms of its crystal-field (CF) wavefunctions. Our theoretical analysis suggested that the magnetic behavior of the compound be governed by these low-lying CF levels in the temperature region at least up to 100 K.