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.