Modulating electronic, magnetic and mechanical properties of MVN (M = Ti, V, Cr) MXenes by surface functionalization

Using first-principles calculations, the electronic, magnetic and mechanical properties of V-based nitride MXene systems, MVN (M = Ti, V, Cr) with symmetrically and asymmetrically functionalized by F, OH and O groups, are examined. We found all the functionalized systems are thermodynamically stable owing to their negative formation energy. Upon appropriate surface functionalization, the studied systems are expected to become semiconductors. For instance, V2NO2 and V2NF2 exhibit metallic behavior whereas V2NOF turns into semiconductor. More importantly, the band structure shows several isolated flat-bands around Fermi level in the MVNOF (M = Ti, V, Cr) systems. Antiferromagnetic (AFM)-ferromagnetic (FM) transition can even be obtained in the functionalized CrVN and TiVN systems. The hardness of MVN (M = Ti, V, Cr) is the greatest in the oxygen symmetrically functionalized systems based on the analysis of the elastic constants and their derived parameters. Our results are expected to shed light on the design of electronic and spintronic devices based on MVN (M = Ti, V, Cr) MXenes.