Neutron-diffraction evidence for the ferrimagnetic ground state of a molecule-based magnet with weakly coupled sublattices

The diruthenium compoundTRu2.O2CMe/4U3TCr.CN/6U contains two weakly coupled, ferrimagnetically ordered sublattices occupying the same volume. Due to the weak, antiferromagnetic dipolar interaction Kc 5 10 3 meV between sublattices, a small magnetic field Hc Kc= B 800 Oe aligns the sublattice moments. Powder neutron-diffraction measurements on a deuterated sample confirm an earlier prediction that the sublattice moments are restricted by the anisotropy of the diruthenium ‘paddle-wheels’ to the cubic diagonals. Those measurements also suggest that quantum corrections to the ground state are significant.