In the present study, we observe how conductivity and magnetism in multiferroic spinels can be modulated through doping. Due to antiferromagnetic interaction between both cobalt-chromium and chromium-chromium ions in CoCr \(_2\) O \(_4\) , the system has a frustrated magnetic structure. However, when the system is doped by iron then due to the dominant Fe-Co antiferromagnetic exchange interactions, the magnetic frustration in the system is overcome and the system becomes a collinear ferrimagnet. Our main focus in the present communication however is to understand how the spinel CoCr \(_2\) O \(_4\) becomes a half-metal as we dope it with iron and replace the Cr ions with Fe ions to gradually convert it into the inverse spinel CoFe \(_2\) O \(_4\) . The system is found to become half-metallic primarily due to the effect of cobalt ions in disordered state at the octahedral sites upon iron doping. This half-metallic nature makes the system suitable for spintronic based applications. The disorder-induced broadening of the otherwise narrow 3d bands of the cobalt species is identified as the primary cause of half-metallicity.
