Magnetic properties of antiferromagnetic two-singlet systems. I. Theoretical phase diagram

Abstract

The phase diagram of an antiferromagnetic two-singlet system is studied within the frame of the molecular-field approximation. Different interactions give for the metamagnetic transition a net of magnetization curves whose analytical expressions are given ; their main properties are considered (threshold field, critical temperature, etc...) along with the problem of the free energy of « non-Kramers » ions. The influence of the splitting of the energy levels upon the metamagnetic transition suggests an analogy between an induced-moment system at 0 °K and a Kramers doublet at non-zero temperature