Magnetic properties of DyNi2B2C studied with a two-ion model for antiferromagnets

In a rare-earth antiferromagnet, two neighboring magnetic ions order spontaneously in opposite directions below the Néel temperature. Especially when it is placed in an external magnetic field, the two magnetic ions react to the field in different ways, so that they usually have different magnitudes and orientations below the magnetic transition temperature. Therefore, to describe the magnetic structure of an antiferromagnet, the single-ion ferromagnetic-like model is inadequate. To solve this problem, a two-ion model for rare-earth antiferromagnets is proposed and used in this work to investigate the magnetic properties of DyNi₂B₂C. The magnetic susceptibility curves obtained with this model show good agreements with experimental data.