Effect of carbon content on magnetostructural properties of Mn3GaC

• Effect of carbon content on magnetostructural transformation in Mn3GaCx has been investigated.
• Increase in C content changes the ground state from FM metallic to AFM semiconducting type.
• This behavior can be understood to be due to increased Mn3d – C2p hybridization
• Magnetic field can be used to modulate the relative strengths of competing magnetic interactions.

Effect of carbon content on magnetostructural transformation in antiperovskites of the type Mn3GaCx (x=0.8, 1.0 and 1.05) has been investigated. It is found that increase in carbon content changes the ground state from ferromagnetic metallic (x=0.8) to antiferromagnetic semiconducting (x=1.05) type. This has been attributed to localization of itinerant Mn 3d electrons due to increased Mn3d – C2p hybridization. Such a hybridization strengthens Mn–C–Mn antiferromagnetic interactions over Mn–Mn ferromagnetic interactions. Further, magnetic field can be used as a tool to modulate the relative strengths of these ferromagnetic and antiferromagnetic interactions thereby affecting the nature and strength of magnetocaloric properties.