Magnetic Compensation in Ferrimagnetic Bimetallic Oxalates

Bimetallic oxalates are layered organic magnets with the chemical formula A[M(II)M'(III)(ox)$_{3}$], where M(II) and M'(III) are transition metal ions, A is an organic cation, and ox = C$_{2}$O$_{4}$ is the oxalate molecule. For some ferrimagnetic bimetallic oxalates, the magnetization changes sign at a compensation temperature below the ferrimagnetic transition temperature. We have initiated a systematic study of these compounds by examining the possibility of magnetic compensation for any possible combination of transition metal ions. Our model includes spin-orbit coupling for both M(II) and M(III) ions, the antiferromagnetic exchange between neighboring metal ions mediated by the oxalate bridges, and the effects of the ligand fields. Using mean-field theory, we predict candidates that may exhibit magnetic compensation for certain choices of the intercalated cation A.