Co-existence of ferromagnetic and antiferromagnetic interactions in Mn₃Ga_(1−x)Sn _xC

The magnetic properties of the Mn₃Ga_(1−x)Sn_xC, 0⩽x⩽1 antiperovskite compounds have been investigated in detail. Though all compounds of this series crystallize in a cubic structure, the Ga rich (x⩽0.2) compounds transform, via a first-order transformation, to an antiferromagnetic ground state and the Sn rich (x⩾0.8) compounds exhibit dominant ferromagnetic interactions at low temperature. In the intermediate range (0.4⩽x⩽0.7) co-existence of ferromagnetic and antiferromagnetic interactions can be seen. The results have been explained to be due to growth of ferromagnetic sub-lattice at the expense of antiferromagnetic sub-lattice with increasing Sn concentration in Mn₃Ga_(1−x)Sn_xC. This growth occurs to a point where the first-order transition is altered from a ferromagnetic–antiferromagnetic type in Ga rich compounds to a paramagnetic–ferrimagnetic type in Mn₃SnC. (papers)