Half-metallic antiferromagnetic in Mn2ZnCa

► The Mn2ZnCa alloy in CuHg2Ti-type structure is predicted to being half-metallic antiferromagnetic nature. ► The equilibrium structure is determinied by minimizing total energy calculations. ► The density of states analysis presents the nature of antiferromagnetic originating from d-d orbital hybridization. ► The lattice constant dependence of magnetic moment exhibit that the antiferromagnetic nature is kept within the wide ranges of lattice constant. ► The changes of atom coordination surroundings lead to the antiferromagnetic nature lost.