Tailoring structure and magnetic properties of NixCo1−x(N(CN)2)2 molecular magnets

• Ni (Co) composition-dependent detailed structural analysis of (Ni,Co) DCA powders were examined.
• Depending on the composition ratio, the ferromagnetic ordering can be tuned.
• Variation of superexchange interaction length due to the different size of the transition metal.
• Origin of tunable ordering temperature is related to the different kind of transition metals.

A series of transition metal NixCo1−x(N(CN)2)2 dicyanamide molecular magnet, 0 ≤ x ≤ 1, was chemically synthesized. Structure and magnetic properties were investigated by IR spectroscopy, neutron powder diffraction and temperature-dependent magnetization measurement. The neutron powder diffraction measurement established that all samples showed the rutile structure with Pnnm space group. The detailed Rietveld refinement results revealed a systematic decrease of unit-cell volume with increasing Ni content. We also observed a concurrent increase of the Curie temperature with Ni content due to the increase of superexchange interaction.